Have you ever wondered why there are so many ...

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.

高三英语任务型阅读中等难度题查看答案及解析

Have you ever wondered ______ there are so many natural disasters across the world in 2010?

A. which it is that                      B. what is it that

C. how it is that                         D. why it is that

高三英语单项填空中等难度题查看答案及解析

Have you ever wondered ______ there are so many natural disasters across the world in 2010?

A．which it is that                                                      B．what is it that

C．how it is that                            D．why it is that

高三英语单项填空困难题查看答案及解析

I wonder _______ there are so many natural disasters across the world in 2010.

A．why is it            B．it is why that       C．why is it that       D．why it is that

高三英语单项填空困难题查看答案及解析

I wonder _______ there are so many natural disasters across the world in 2010.

A．why is it                        B．it is why that               C．why is it that               D．why it is that

高三英语单项填空简单题查看答案及解析

I wonder _______ there are so many natural disasters across the world in 2010.

A．why is it　　　　　　　　　 　　　　　　　　　 　　　　　　　　　 B．it is why that　　　　　　　　　 　　　　　　　　　 C．why is it that　　　　　　　　　 　　　　　　　　　 D．why it is that

高三英语单项填空中等难度题查看答案及解析

Have you wondered why different animals or pests have their particular colors? Colors in them seem to be used mainly to protect themselves.

Birds, especially seagulls are very fond of locusts, but birds can’t easily catch locusts because locusts change their colors together with the change of the color of crops. When crops are green, locusts look green. But when crops are ripe, locusts take on exactly the same brown color as crops have. Some other pests with different colors 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 coloring 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 color much like the barks(树皮) 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 is over, its enemies cannot find it, and it quickly 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 color 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 colors

2.Locusts are ______ but they aren’t easily wiped out(消灭)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 colors as crops

D. birds; they fly very fast

3.What does the underlined word “invisible” in Paragraph 3 mean?

A. can’t be seen    B. can be seen     C. can’t move      D. can’t change

高三英语阅读理解中等难度题查看答案及解析

One of the most dangerous insects you need to watch out for during summer is mosquitoes. But no matter how you try to avoid them, some people naturally attract mosquitoes more than others.

One of the most important facts to remember is that mosquitoes track people down by smell and body odour(气味), according to Bart Knols, PhD, a biologist devoted to the study of mosquitoes. The carbon dioxide people breathe out, along with chemicals from the skin, creates an “odour plume” that mosquitoes can detect from up to almost 100 feet away. “Each person gives off more than 300 chemicals from the skin, more than 100 in breathing out,” Knols says.

The specific mixtures on the skin that mosquitoes respond to vary by species. The yellow fever mosquito and Asian tiger mosquito, for example, respond well to lactic acid from skin. African malaria mosquitoes respond to a mix of fatty acids, according to Knols. Your individual mixtures and smells determine how much of a mosquito attraction you are, depending on the mosquito species. The mix of chemicals you produce are only partly in your control. These chemicals depend on your genetic make-up, health condition, diet, skin pH, and so on. “Bacteria(细菌)on the skin break down the mixtures that we give off through our pores(毛孔), and these are the attractive smells,” Knols says. “So it is not actually we that attract mosquitoes, but the bacteria on our skin.”

Although this is a complex and partly understood phenomenon, Knols says that we do all have a unique smell. There are many folk stories about why some people are more or less attractive to mosquitoes. Some people falsely think the blood type is the cause, and others believe taking vitamin B or eating garlic makes people less attractive to mosquitoes—but Knols notes there’s no scientific data backing these claims.

1.What do we learn from the second paragraph?

A.Mosquitoes can detect people with smell. B.Nobody can avoid mosquitoes anyway.

C.A person breathes out over 300 chemicals. D.People naturally attract mosquitoes.

2.Why does the author take several kinds of mosquitoes for example?

A.To persuade readers to protect the environment.

B.To warn people against touching mosquitoes.

C.To show different mosquitoes react to mixtures.

D.To make people look out for poisonous mosquitoes.

3.What draws mosquitoes according to Bart Knols?

A.Chemicals in the mouth. B.Mixtures people give off.

C.Smells from the pores. D.Bacteria on the skin.

4.What is the best title for the text?

A.The Scientific Reason You Are a Mosquito Attraction

B.Folk Stories about How Mosquitoes Attack People

C.Attitudes toward Mosquitoes Different People Have

D.Ways to Make People More and More Attractive

高三英语阅读选择中等难度题查看答案及解析

Have you ever wondered why some people are able to have confidence to spare when it comes to taking risks such as starting their own business or taking a year off to travel without an enormous safety net? The answer is that they’ve 　　 the art of optimistic thinking. The good news is that 　　 some people are simply born to be optimistic, anyone can 　　 to take a more positive approach towards their life.

Optimists look for 　 outcomes. This doesn’t mean that optimists always jump into things carelessly and hope for 　 , rather that they do not let potential negative outcomes 　 the potential positive outcomes. By hoping so and having 　 that they can handle any negatives, optimists are 　 to take advantage of opportunities that come their way.

Optimists believe that their actions can make a 　 . They do not see their own efforts as being 　　 . They understand that they do have the power to make things happen and take steps to make their dreams a reality. 　 , pessimists have a difficult time believing that what they do will make any difference and find it 　 to make any changes or take any action towards achieving a goal. They find 　 why something that has worked for others will not work for them and believe that anything they do is certain to 　 . This makes it difficult for them to get out of situations that make them 　 , such as a dead-end job that makes them miserable.

Optimists do not internalize(使内在化)failure. When things don’t 　 for them, they don’t beat themselves up over it. They are able to accept failure as a part of life and try 　 with a positive attitude. They are often better able to learn from their 　 . When pessimists do take chances and fail, they have a hard time not 　 themselves and concluding that this is the way that it has to be. One 　 can leave them with a sense of being unworthy or completely at the mercy of others.

That’s why optimists become successful!

1.A. understood 　　　 B. mastered　　　　 C. studied 　　　 D. found

2.A. if 　　 　　　　　　 B. because 　 　　 C. unless 　 　　　 D. while

3.A. respond 　　　　 B. continue 　　 C. learn 　 　　　　 D. return

4.A. positive 　　　 B. possible　　　　 C. different 　　 D. particular

5.A. the worst 　　　　 B. the least　　　 C. the best 　　　 D. the most

6.A. overcome 　　　 　 B. overlook　　　　 C. overload 　　　 D. overtake

7.A. faith 　 　　　　　 B. work 　 　　　　 C. trouble 　　 D. control

8.A. eager　 　　　　　 B. unwilling 　　 C. ready 　 　　　　 D. likely

9.A. change 　　　　　 B. difference 　 C. fortune 　　 D. fame

10.A. endless 　　　　 B. precious　　　　 C.special 　　　　 D. meaningless

11.A. In fact　　　　 B. In general　　 C. In contrast 　 D. In short

12.A. rewarding 　　　 B. amazing　　　　 C.difficult　　　　 D. impossible

13.A. excuses 　　　　 B. causes　　　　　 C. explanations D. faults

14.A. end 　　 　　　　　 B. start 　　　　 C. fail 　 　　　　 D. fall

15.A. responsible 　　 B. unhappy　　　　 C. competitive D. unclear

16.A. run out 　　　　 B. make out　　　　 C. work out 　　　 D. look out

17.A. hard 　　 　　　　 B. out 　 　　　　　 C. again　 　　　　 D. instead

18.A. experience 　　 B. mistakes　　　　 C. friends 　　　　 D. faiths

19.A. blaming 　　　 　 B. protecting　　 C. identifying 　 D. presenting

20.A. case 　　 　　　　 B. defeat 　　　　 C. state 　　 　　　 D. example

高三英语完形填空中等难度题查看答案及解析

Have you ever wondered why certain pop songs just make you feel so good?

Researchers studying the question found that the right combination of uncertainty and surprise is what gives listeners the most pleasure.

The study, published in the journal Current Biology, involved an analysis of 80,000 chords( 和弦)in 745 pop songs from the US Billboard “Hot 100” chart between 1958 and 1991.

The researchers - from institutes in Germany, Norway, Denmark and the UK - used a machine-learning model to quantify the level of uncertainty and surprise of these chords, and then asked 39 adult volunteers to rate how pleasurable they found each series of chords.

Each song was stripped of its melody and lyrics(歌词)so that only chord progressions were left and the results couldn’t be influenced by other associations to the songs that listeners might have had.

They found two things: that participants got greater pleasure when they were relatively certain what would happen next but then were surprised by an unexpected chord progression. However, the same number of participants found it pleasant when they were uncertain as to what would follow, and then the subsequent chords were more familiar to them.

“It is fascinating that humans can get pleasure from a piece of music just by how sounds are ordered over time,” Vincent Cheung, the lead researcher on the paper from the Max Planck Institute for Human Cognitive and Brain Sciences, Germany, said in a statement.

“Songs that we find pleasant are likely those which strike a good balance between knowing what is going to happen next and surprising us with something we did not expect. Understanding how music activates our pleasure system in the brain could explain why listening to music might help us feel better when we are feeling blue.”

Cheung told CNN that pleasure in music has a lot to do with what listeners expect. Previous studies had looked into the effects of surprise on pleasure, but he and his colleagues’ study also focused on the uncertainty of listeners’ predictions.

The findings may help improve artificial musical algorithms(算法)and could help composers write music or predict musical trends.

“The idea is that hopefully as a scientist analyzing these patterns of pleasure in humans, you can somehow work out where music can go next,” Peter Harrison, a researcher at Queen Mary University, London, who worked on the project, told CNN.

As part of the same experiment, the researchers also used brain imaging to locate the areas of the brain reflected in musical pleasure. They found the regions involved were the amygdala, the hippocampus and the auditory cortex, which process emotions, learning and memory, and sound, respectively.

Cheung added that another part of the brain, the nucleus accumbens - which processes reward expectations - was perhaps responsible for “directing our attention towards the music so that we will try to find out what will happen next.”

1.This passage mainly deals with _____.

A.how composers create pop music trends B.why popular music makes people happy

C.what kind of music makes people most happy D.which part of the brain produces happy music

2.The underlined words in Paragraph 5 have the closest meaning to _____.

A.reserved B.restored C.removed D.refreshed

3.We can learn from the passage that __________.

A.pleasure in music is connected with listeners’ expectations

B.findings of this study are of little help to music composing

C.the regions of the brain mentioned process music composing

D.only uncertainty followed by familiarity can bring about pleasure

高三英语阅读理解中等难度题查看答案及解析