Have you ever wondered why there are so many skin colors in the world? Do you know why people living in particular areas usually have a certain color? Biology and history are the two reasons for this.
Skin contains something called melanin, which determines a person’s skin color. The more melanin a person has, the darker his or her skin will be. The amount of and the production of melanin are controlled by genetics, but can be affected by other things, such as sunlight. If a person lives in a place with less sunlight, a person’s body will produce less melanin, making the skin lighter.
Skin color is also affected by another source ---- vitamin D. humans all need vitamin D to build bones. People can get it by eating foods such as fish and milk, or from sunlight, so sunlight absorbed by melanin cannot be used for vitamin D production. Therefore, a dark—skinned person will produce less vitamin D than a light—skinned person when they received the same amount of sunlight.
The connection between vitamin D production and skin color is clear when we look at evolution. The earliest humans lived in Africa, their dark skin produced less vitamin D because of their dark skin. As a result, their skin made less melanin, so they could get enough sunlight to produce vitamin D. their skin gradually got lighter and they lost hair. Now, people living in areas with strong sunlight like Africa, have darker skin, while people living in other areas have lighter skin. The exception to this is the Inuit, who live in a place with little sunlight, but have dark skin because they eat a lot of fish and have enough vitamin D.
Evolution has given us a rainbow of skin colors. Humans have always had melanin to determine our skin color. What has changed through history is the environment where we have lived. This has in turn changed our melanin production, and eventually, skin color.
Brief 1 | People living in a particular 2usually have the same skin color and there are many different skin colors in the world. |
Reason for skin color | The reasons for different skin colors mainly3in biology and history. |
Biology reasons | The amount of melanin, by which a person’s skin color is __4 , varies from people to people. The more melanin a person has, the __5 his or her skin will be. Vitamin D is another source6 skin color. Vitamin D is necessary for humans to build bones. Sunlight contributes to vitamin D in the skin. |
Historical reasons | The earliest people in Africa hioknj006Dad dark skin with hair covering it because the sunlight is very strong. When they moved to places where they could not get enough sunlight to __7___ vitamin D, their skin color became lighter. Generally speaking, people in areas with strong sunlight, have darker skin ____8people in other areas have lighter skin. |
9 | Melanin 10 an important role in our skin color. With our living environment changing, melanin production is changed, which leads to the changes in our skin color. |
高二英语阅读理解中等难度题
Have you ever wondered why there are so many skin colors in the world? Do you know why people living in particular areas usually have a certain color? Biology and history are the two reasons for this.
Skin contains something called melanin, which determines a person’s skin color. The more melanin a person has, the darker his or her skin will be. The amount of and the production of melanin are controlled by genetics, but can be affected by other things, such as sunlight. If a person lives in a place with less sunlight, a person’s body will produce less melanin, making the skin lighter.
Skin color is also affected by another source ---- vitamin D. humans all need vitamin D to build bones. People can get it by eating foods such as fish and milk, or from sunlight, so sunlight absorbed by melanin cannot be used for vitamin D production. Therefore, a dark—skinned person will produce less vitamin D than a light—skinned person when they received the same amount of sunlight.
The connection between vitamin D production and skin color is clear when we look at evolution. The earliest humans lived in Africa, their dark skin produced less vitamin D because of their dark skin. As a result, their skin made less melanin, so they could get enough sunlight to produce vitamin D. their skin gradually got lighter and they lost hair. Now, people living in areas with strong sunlight like Africa, have darker skin, while people living in other areas have lighter skin. The exception to this is the Inuit, who live in a place with little sunlight, but have dark skin because they eat a lot of fish and have enough vitamin D.
Evolution has given us a rainbow of skin colors. Humans have always had melanin to determine our skin color. What has changed through history is the environment where we have lived. This has in turn changed our melanin production, and eventually, skin color.
Brief __71__ | People living in a particular __72__ usually have the same skin color and there are many different skin colors in the world. |
Reason for skin color | The reasons for different skin colors mainly__73__ in biology and history. |
Biology reasons | The amount of melanin, by which a person’s skin color is__74__ , varies from people to people. The more melanin a person has, the __75__ his or her skin will be. Vitamin D is another source__76__ skin color. Vitamin D is necessary for humans to build bones. Sunlight contributes to vitamin D in the skin. |
Historical reasons | The earliest people in Africa had dark skin with hair covering it because the sunlight is very strong. When they moved to places where they could not get enough sunlight to__77__ vitamin D, their skin color became lighter. Generally speaking, people in areas with strong sunlight, have darker skin __78__ people in other areas have lighter skin. |
__79__ | Melanin__80__an important role in our skin color. With our living environment changing, melanin production is changed, which leads to the changes in our skin color. |
高二英语其他题中等难度题查看答案及解析
Have you ever wondered why there are so many skin colors in the world? Do you know why people living in particular areas usually have a certain color? Biology and history are the two reasons for this.
Skin contains something called melanin, which determines a person’s skin color. The more melanin a person has, the darker his or her skin will be. The amount of and the production of melanin are controlled by genetics, but can be affected by other things, such as sunlight. If a person lives in a place with less sunlight, a person’s body will produce less melanin, making the skin lighter.
Skin color is also affected by another source ---- vitamin D. humans all need vitamin D to build bones. People can get it by eating foods such as fish and milk, or from sunlight, so sunlight absorbed by melanin cannot be used for vitamin D production. Therefore, a dark—skinned person will produce less vitamin D than a light—skinned person when they received the same amount of sunlight.
The connection between vitamin D production and skin color is clear when we look at evolution. The earliest humans lived in Africa, their dark skin produced less vitamin D because of their dark skin. As a result, their skin made less melanin, so they could get enough sunlight to produce vitamin D. their skin gradually got lighter and they lost hair. Now, people living in areas with strong sunlight like Africa, have darker skin, while people living in other areas have lighter skin. The exception to this is the Inuit, who live in a place with little sunlight, but have dark skin because they eat a lot of fish and have enough vitamin D.
Evolution has given us a rainbow of skin colors. Humans have always had melanin to determine our skin color. What has changed through history is the environment where we have lived. This has in turn changed our melanin production, and eventually, skin color.
Brief 1 | People living in a particular 2usually have the same skin color and there are many different skin colors in the world. |
Reason for skin color | The reasons for different skin colors mainly3in biology and history. |
Biology reasons | The amount of melanin, by which a person’s skin color is __4 , varies from people to people. The more melanin a person has, the __5 his or her skin will be. Vitamin D is another source6 skin color. Vitamin D is necessary for humans to build bones. Sunlight contributes to vitamin D in the skin. |
Historical reasons | The earliest people in Africa hioknj006Dad dark skin with hair covering it because the sunlight is very strong. When they moved to places where they could not get enough sunlight to __7___ vitamin D, their skin color became lighter. Generally speaking, people in areas with strong sunlight, have darker skin ____8people in other areas have lighter skin. |
9 | Melanin 10 an important role in our skin color. With our living environment changing, melanin production is changed, which leads to the changes in our skin color. |
高二英语阅读理解中等难度题查看答案及解析
Have you ever wondered why successful people are so successful? Habits play an essential role in shaping our lives. We all know that bad habits can be harmful to your mental and physical well-being. 1. Good habits, on the other hand, can help you rise above others and be at your best. So, what are the common habits of successful persons that set them apart from the rest of us?
2. Most successful figures spend half an hour or more on newspapers, magazines and other books on a daily basis. Most of them have a preference for non-fiction piece that include history, self-help books, and biographies.
Getting up early. The majority of successful people rise approximately 3 hours before their actual workday starts. It gives them adequate time to get additional things done, which may include completing side projects, working out, or just planning ahead. 3.
Working out and staying in shape. We all know the benefits of a healthy lifestyle especially working out and staying physically fit. 4. Clearing your mind and challenging yourself physically with a tough workout daily helps you stay ready for the daily challenges of a business. To sum it up, a strong body carries a strong mind.
Working on communication skills. Communication plays a key role in building constructive interpersonal relationships on a personal as well as on a professional level. 5. However, if you are unable to convey the right information and message in a timely manner, you are less likely to achieve your goals. As with other skills, it is vital to continuously work on improving communication to help you stay more efficient while communicating with anyone on any level.
A. Applying technology.
B. Keeping reading as a habit.
C. After all, the early bird catches the worm.
D. Developing a healthy lifestyle is demanding.
E. Working with data, facts, and figures is important.
F. Successful people require mental and physical fitness.
G. They can block your road to achievement and success.
高二英语七选五困难题查看答案及解析
Have you ever wondered why certain people always say they are lucky? Some people say the secret of being born lucky is probably a summer birthday. May babies are the most likely to enjoy a lifetime of good fortune, a study of 40,000 people has found. The time of year you are born has a lasting influence on optimism and whether people think they are lucky, British and Swedish scientists said. May is the luckiest month to be born in, with half of those born then considering themselves lucky. October is the least lucky month with only 43 percent claiming good fortune.
The study adds to evidence that luck is not all down to chance, but is also affected by a person’s attitude. Another research has shown that whether people think themselves lucky depends more on having a “glass half-full” (instead of “half-empty”) approach to life, than on success. Professor Richard Wiseman, who led the study, said, “Something is influencing how people feel about their luck. People create their own luck through their attitude towards life.”
Luck is a mental state and not a matter of blind chance. There could be two reasons why those born in spring and summer reported themselves luckier than those born in autumn or winter. “One theory is that the temperature at the time of birth might be helpful to the development of the brain.” He said. “People born in winter are more likely to suffer from depression”. He said another possible reason is that mothers may be in a bad mood during winter, which influences their babies. The researchers said their findings were based on statistics only, and would not be true for everyone.
What’s depression? Medical depression is when one feels so sad and hopeless that sometimes he can’t imagine being happy. The pain becomes so deep that you don’t feel like participating in life. People who are permanently depressed usually have physical problems like stomachaches, headaches, and lack of energy. As you probably know, some people experience such deep depression that they believe suicide (killing yourself) is the only way to escape their pain.
1.Why can your birthday influence your attitude towards life?
A. The time of your birthday determines how fortunate you will be.
B. Mothers may feel differently in different seasons, and their moods influence their babies.
C. How successful you will be lies in the hour of your birthday.
D. How you feel about your health is influenced by the time of your birthday.
2.Having a “half-full” approach to life is a (an) ______ attitude.
A. optimistic B. pessimistic C. lucky D. depressing
3.Which of the following is NOT true according to the passage?
A. People born in summer are probably more optimistic than those born in winter.
B. A person’s luck may be affected by his attitude.
C. Depression may harm one’s physical health.
D. Luck is never a matter of chance.
4.According to the research result, one’s luck mainly depends on ______.
A. chance B. the month to be born in
C. one’s attitude to life D. health state
高二英语阅读理解中等难度题查看答案及解析
.
Have you ever wondered why different animals or pests have their particular colours? Colours in them seem to be used mainly to protect themselves.
Birds, especially seagulls, are very fond of locusts, but birds cannot easily catch locusts because locusts change their colours together with the change of the colour of crops.When crops are green, locusts look green.But when crops are ripe, locusts take on exactly the same brown colour as crops have.Some other pests with different colours from plants are usually easily found and eaten by their enemies.So they have to hide themselves in terror for lives and appear only at night.
If you study the animal life in any part of the world, you will find the main use of colouring is to protect themselves.Bears, wolves and other beasts move quietly through forests.They are usually invisible to the eyes of hunters, because they have the colour much like the barks of trees.
An even more strange act remains to be noticed.A kind of fish living in seas can send out a kind of very black liquid when it faces danger.While the liquid spreads over, its enemies cannot find it, and it immediately swims away.Thus, it has existed up to now though it is not powerful at all.
1.This passage mainly talks about ________.
A.the change of colour in locusts
B.the protective coloration of animals and pests
C.how a certain sea fish protects itself
D.animals or pests can dye themselves different colours
2.Locusts are ________ but they are not easily wiped out by their enemies because ________.
A.animals; they are powerful enough
B.beasts; they are dangerous to their enemies
C.pests; they take on the same colours as crops
D.birds; they fly extraordinarily fast
3.The pests that have different colours from plants usually appear at night because ________.
A.their enemies can easily find them and eat them
B.they have the habit of coming out in darkness
C.it’s easy for them to destroy plants in darkness
D.birds take their rest when night comes
4.Bears and wolves have the same colour as barks of trees because ________.
A.they fear other beasts
B.they like brown or grey colours
C.they enjoy walking through forests quietly
D.the colours help prevent themselves from being noticed
高二英语阅读理解中等难度题查看答案及解析
Have you ever wondered what the longest word in the English language is? Believe it or not, there’s no simple answer to the question. You might think it would be as easy as opening a dictionary and looking for the longest word. However, it’ s far more complicated than that.
Over time, many people have suggested many different words for the title of the longest word in English. How can that be? That’s because the first thing that people have different opinions on is what should be considered a word. Some of the words were simply made up to be the longest! For example, there is one really famous long word that most kids know. It comes from Disney’s movie Mary Poppins: supercalifragilisticexpialidocious, which means wonderful. But since that 34-letter word was made up simply to be sung as a song in a movie, should it count?
How about long words that actually describe something in the world? Scientists have come up with several possible choices. The name of a virus totals 1, 185 letters. There’s also a protein whose name totals 1, 909 letters. Should these win the title? “Not so fast!” say some people. Are these words ever actually used? Can they even be pronounced? And are they meaningful just because they are made up to be long?
If you’re wondering about some long words in common English, here are some examples. Those words include uncharacteristically (20 letters), deinstitutionalization (22 letters) and counterrevolutionaries (also 22 letters). Or perhaps the word “smiles” is the longest word in English. Sure, it has only six letters, but there is a “mile” between the first and the last letters!
1.What is the first thing to consider when we decide the longest word?
A.Whether it is a real word. B.Whether it can be pronounced.
C.Whether it is used in daily life. D.Whether it can be understood.
2.Why does the author mention the underlined questions in paragraph 3?
A.To express the writer’s concern. B.To compare different ideas.
C.To amuse readers. D.To show people’s doubt.
3.How does the author sound in the last paragraph?
A.Proud. B.Humorous.
C.Excited. D.Surprised.
4.The text is mainly about _________________________.
A.English words change a lot as time goes by
B.it is hard to decide what the longest word is
C.long words are often used in scientific fields
D.why we can’t understand some English words
高二英语阅读理解中等难度题查看答案及解析
There are so many things we do in our daily lives that have become a "habit".1.How you answer the phone is a habit. The way you sit in the car when you drive is a habit. Have you ever tried to change the way you do something, after you ve done it in a certain way for so long? It's not very easy to do. The minute your mind drifts to something else, you go right back to the old way of doing things.2.it's a way of doing things that has become routine or commonplace. To change an existing habit or form a new one can be a boring task.
Let's pick something fairly easy to start with, like spending 15 minutes in the morning reading a book. If you want to turn something into a habit that you do every day, you have to WANT to do it.3.Make a firm decision to do this on a daily basis.
Imprint it in your mind. Write several notes to yourself and put them in places where you will see them. By the alarm clock, on the bathroom mirror, on the refrigerator door, in your briefcase, and under your car keys are good places to start.
After the newness wears off, then you will have to remind yourself, "Hey, I forgot to..." Keep using the notes if you have to.4.Some people say it will take over a month to solidify it and make it something you will do without having to think about it. I tend to agree with the last statement. Two to three weeks will help you to remember, but thirty days or more will make it a part of your everyday routine.5.
A. What is a "habit" anyway?
B. Forming a bad habit is easy.
C. Brushing your teeth is a habit.
D. Is doing things in an old way good?
E. If you don't, you will find a way to do everything but that.
F. It takes 16 to 21 times of repeating a task to make it a habit.
G. that's something you won't necessarily have to think about before you do it—habit.
高二英语七选五中等难度题查看答案及解析
Have you ever complained why life is so tiring? Does the sky sometimes seem dark to you? Are your studies sometimes not successful? Well, friends, cheer up and smile all the time. If you see the world with your warm heart, you’ll find that the whole world smiles to you.
While in school, sometimes you are tired of your lessons, but have you ever noticed the happy smile on your teacher’s face when you did a good job?
One day it is fine. Just before you go out, it suddenly starts to rain. Maybe you would feel very sad and start to complain about the weather. But dear friends, why don’t you sit down and listen to the free concerts that the nature offers you? And with the timely rain, crops in the fields will grow better and better and farmers will have a good harvest.
Although everyone wants to succeed in what he tries to do, sometimes failure can’t be avoided. I think failure is not terrible, and the terrible thing is that we are afraid of it and give up hope. When we face failure, we must be confident in ourselves, draw a useful lesson from it and try our best to finish what we have decided to do. As a popular saying goes, “Failure is the mother of success”.
Attitude decides everything. With an optimistic attitude life is easy and pleasant. Let’s smile to whatever we meet and the whole world will smile to us.
1.People sometimes complain _________.
A. the sky is always dark
B. their studies are successful
C. they see the world with their heart
D. life is tiring
2.When we face failure, we ___________.
A. must be confident in ourselves
B. shouldn’t be afraid of it
C. shouldn’t give up hope
D. All of the above
3.The best title for the passage is_______.
A. Smile and the World Smiles to You
B. Complaining about Life
C. Failure is the Mother of Success
D. It is Very Hard to Succeed
高二英语阅读理解中等难度题查看答案及解析
Ever wonder why sometimes a hug is all you need ? You can’t explain it , but there’s just something comforting about being in your wife’s arms after a rough day or giving mom a hug after a long time apart .
A new study says the warm feeling in a hug is more than just skin deep . Researchers from the University of California , Berkeley believe that this loving feeling could have anti-aging benefits .
Oxytocin , sometimes referred to as the “ love hormone(荷尔蒙)” or the “ trust hormone , ” is responsible for those indescribable feelings we get when we’re bonding with a lover or a loved one .
Levels of the hormone drop as we age , and evidence suggests that could be a contributing factor to the deterioration of our bodies as we age . Muscle loss in particular is one of the major side effects of aging , with our bodies losing up to 5 percent of our muscle mass each decade past our 30s .
In the study , published in the journal Nature Communications , researchers injected oxytocin into older mice with muscle damage . The older mice had lower levels of the homeone than younger mice initially . But after nine days , the older mice who were given the hormone healed better than those who did not . In fact , their ability to repair muscle damage was up to 80 percent that of the younger mice .
The results were not only fast-acting , but provide hope for future uses of the hormone in a variety of anti-aging capacities . “ This is good because it demonstrates that extra oxytocin improves aged tissue stem cells(组织干细胞)without making muscle stem cells divide uncontrollably , ” study co-author Wendy Cousins said in a statement .
Previous uses of anti-aging molecules have also been associated with higher cancer risk , but researchers are hopeful that oxytocin can be useful in humans without this risk . In the future , researchers of Berkeley say oxytocin could be used to fight other age-related health issues by improving bone health and even being used as an alternative to hormone replacement therapy .
Now go out and give someone a hug .
1.According to the passage , oxytocin __________ .
A. decreases when people get older
B. creates loving feeling on the skin
C. leads to the great loss of muscles
D. can be used in humans without any risk
2.The underlined word “ deterioration ” in Paragraph 4 probably refers to the state of __________ .
A. getting fatter B. becoming worse or less
C. growing stronger D. dividing uncontrollably
3.What can be learned from the research ?
A. All the older mice healed faster in the research .
B. Older mice healed better than younger ones after 9 days .
C. Extra oxytocin in older mice controlled muscle cell division .
D. Mice with oxytocin injection improved the ability to repair muscle damage .
4. What can be a suitable title for the passage ?
A. When Do We Need A Hug ?
B. A New Anti-aging Product
C. Hugs Having Healing Power
D. How Can We Grow Muscles ?
高二英语阅读理解中等难度题查看答案及解析
If you live in the country or have ever visited there, ____ are that you have heard birds singing to welcome the new day.
A.thinks B.facts C.chances D.possibilities
高二英语单项填空困难题查看答案及解析