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Floods are second only to fire as the most common of all natural disasters.They occur almost everywhere in the world,resulting in widespread damage and even death.Consequently,scientists have long tried to perfect their ability to predict floods.So far,the best that scientists can do is to recognize the potential for flooding in certain conditions. There are a number of conditions,from deep snow on the ground to human error,which cause flooding.
When deep snow melts it creates a large amount of water.Although deep snow alone rarely causes floods,when it occurs together with heavy rain and sudden warmer weather it can lead to serious flooding.If there is a fast snow melt on top of frozen or very wet ground,flooding is more likely to occur than when the ground is not frozen.Frozen ground or ground that is very wet cannot absorb the additional water created by the melting snow.Melting snow also contributes to high water levels in rivers and streams.
Rivers that are covered in ice can also lead to flooding.When ice begins to melt,the surface of the ice cracks and breaks into large pieces.These pieces of ice move and float down the river,They can form a dam in the river,causing the water behind the dam to rise and flood the land upstream.If the dam breaks suddenly,then the large amount of water held behind the dam can flood the areas downstream too.
Broken ice dams are not the only dam problems that can cause flooding.When a large human-made dam breaks or fails to hold the water collected behind it,the results can be devastating.Dams contain such huge amounts of water behind them that when sudden breaks occur,the great force of the water is like a great tidal wave.The dam waters can travel tens of kilometres,cover the ground in metres of mud and litter,and drown and crush every thing and creature in their path.
Although scientists cannot always predict exactly when floods will occur,they do know a great deal about when floods are probably going to occur.Deep snow,ice-covered rivers,and weak dams are all strong conditions for potential flooding.
1.Which of the following shows the structure of the passage?
("P" stands for "Paragraph".)
A. 
B. 
C. 
D. 
2.Why does frozen ground probably contribute to flooding when deep snow melts?
A. It is likely to form an ice dam.
B. It is too hard for water to run off.
C. It cannot take in more water.
D. It makes the snow melt too quickly.
3.Which of the following words has the closest meaning to the underlined word "devastating" in Paragraph 4?
A. Positive. B. Disappointing.
C. Impressive. D. Damaging.
4.What is mainly talked about in the passage?
A. How floods come into being. B. Where floods usually occur.
C. Why floods do huge damage. D. How to prevent floods effectively.
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Depression is the second most common cause of disability worldwide after back pain, according to a review of research. The disease must be treated as a global public health priority (优先考虑的事), experts report in the journal PLOS Medicine. The study compared depression with more than 200 other diseases and injuries as a cause of disability. “Globally, only a small part of patients have opportunities to be treated,” the World Health Organization (WHO) says.
Depression was ranked at number two as a global cause of disability, but its effects varied in different countries and regions. For example, rates of major depression were highest in Afghanistan and lowest in Japan. In the UK, depression was ranked number three in terms of years when people lived with a disability.
Dr Alize Ferrari from the University of Queensland’s School of Population Health led the study. “Depression is a big problem and we definitely need to pay more attention to it than we do now,” she told BBC News. “There’s still more work to be done in terms of awareness of the disease and also successful ways of treating it. The burden is different between countries, so the rate of depression tends to be higher in low and middle income countries and lower in high income countries.” Policy-makers have made an effort to bring depression to the forefront, but there is still a lot more work to be done.”
“There’re lots of confusions we know related to mental health,” Prof. Alize Ferrari explained. “What one person recognizes as disabling might be different to another person and might be different across countries as well, there are lots of cultural effects and explanations that are related to depression, which makes it more important to raise awareness of the size of the problem and also signs and how to find depression.”
The data—for the year 2010—follows similar studies in 1990 and 2000 looking at the global burden of depression. Commenting on the study, Dr Daniel Chisholm, a health economist at the department of mental health and substance abuse (药物滥用) at the WHO said depression was a very disabling condition.
“It's a big public health challenge and a big problem to be thought about but not enough is being done. Around the world only a tiny part of people get any sort of treatment or diagnosis.” Dr Daniel Chisholm said.
The WHO recently started a global mental health action plan to raise awareness of depression among policy-makers.
1. According to the passage, which of the following ranks NO. 1 among the causes of disability?
A. Cancer. B. Depression.
C. Back pain D. Heart disease.
2.What can we learn from the first paragraph?
A. Depression has been treated as a global public health priority.
B. PLOS Medicine is a website dealing with medical problems.
C. The study only analyzes depression all over the world.
D. Most patients with depression haven’t been treated.
3.Who is Alize Ferrari?
A. She is a doctor working in a hospital.
B. She is a professor at a university leading the study.
C. She is an official from the government.
D. She is a common teacher taking part in the study.
4.Which of the following is TRUE according to Paragraph 4?
A. There is a common standard of recognizing disability worldwide.
B. Most reasons for disability are similar.
C. Mental health has raised much attention among people.
D. How to find patients suffering from depression is not easy.
5.Why did the WHO start a global mental health action plan?
A. To make policy-makers of all countries pay attention to the problem of depression.
B. To help patients become healthier.
C. To raise the status of doctors in the world.
D. To help build more colleges that study mental health.
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Drowning is the second-most common cause of accidental death in children aging 1 to 14 (just behind motor vehicle accidents.) In a study by a national safety group, 90 percent of children who drowned did so while under the care of an adult or teenager. 1..
They are gasping(急促吸气)
2.. And for young children, who are in a horizontal face-down position, they are unable to keep the mouth above the water’s surface at all.
3.
They have to be able to breathe before they can speak. When people are drowning, their mouths sink below and reappears above the surface of the water. There isn't time for them to exhale, inhale, and call out.
They don’t seem in trouble
Sometimes the most important indicator that people are drowning is that they don’t look like they are drowning. They may just seem to be looking up at the sky, shore, pool deck, or dock. Ask them, “Are you all right?” If they cannot answer at all, they probably are drowning. 4..
They are trying and failing, to swim in a particular direction
A drowning victim can’t make any forward progress while in the water, according to the American Red Cross. “A young child may appear to be doing a ‘doggy paddle’ but has no forward progress,” according to the official lifeguarding guide. 5..
A．They can’t call for help
B．They can’t wave for help
C．All efforts are devoted strictly to getting air
D．Here are the steps for you to follow when someone is drowning
E．They could also take in water when drowning victims are gasping for air
F．You may have less than 30 seconds to get to them if they return a blank stare
G．Watch for these signs that someone is in trouble to avoid a tragedy in the making
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All sorts of items become litter(垃圾) but two of the most common and most dangerous are cigarette butts（烟头) and plastic bags. Litter is a big problem for our environment but it is a problem that individuals can easily do something about. Not littering at all or cleaning up litter, such as cigarette butts and plastic bags, greatly improves the quality of our environment.
Although cigarette butts, are small, they are bad for the environment. Over 1,600 billion cigarette are smoked each year in China and large quantities of the butts are thrown away. Worldwide, about 4. 5 trillion butts are littered every year. Apart from the fact that butts spoil the beauty of the environment, they contain some very toxic chemicals. These find their way into the water supply where they decrease the quality of the water and endanger plants and animals that live there. So, if people have to smoke, they shouldn't throw away the butts but put them in the rubbish bin instead.
Plastic bags are another common form of litter that is a danger to the environment. There areseveral reasons for this. They are made from oil and gas, which are non—renewable resources. If they are not recycled, these resources are lost to us. In China, 2 billion plastic bags are used every day. An enormous number of these become litter. This is a huge problem because they last from 20 to 1,000 years in the environment. They float easily in the air and water and travel long distances. They find their way to rivers, parks, beaches and oceans. Plastic bags kill up to one million seabirds, 100, 000 sea mammals and countless fish each year worldwide. It is up to people not to let plastic bags become litter. It would be better if they used fewer and recycled them.
Cleaning up your cigarette butts and plastic bags would improve the environment. And we would know that we were doing something to look after our planet. However, I believe the best solution would be not to smoke or use plastic bags at all.
1. Which of the following best shows the structure of the passage?
A B. C. D.
( ①= paragraph 1; ②= paragraph 2; ③= paragraph 3; ④a paragraph 4 )
2.The word “toxic” in the paragraph 2 most probably mean “________”
A. precious B. extra C.poisonous D. useless
3. From the text. we know the fact that_________
A. Chinese smokers litter up to 4. 5 trillion butts every year
B. people in the world use 2 billion plastic bags in a single day
C. plastic bags cause 1 million deaths of seabirds each year worldwide
D. the butts can last 20 to 1,000 years in the environment of China
4. What's probably the best title of the passage?. Clean Up Your
A. Say Goodbye to Smokin B. Protect the Endangered Sea Animals . C.Use Paper Bags Now D.Clean Up Your Butts and Bags
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Of all nature's disasters, forest fires are often considered the most frightening. Moving at lightning speed, huge walls of flames can burn acres of land in just a few minutes. And although technology, including the use of fire-retardant chemicals, has greatly helped the fight against forest fires, they still do great damage.
According to the National Interagency Fire Center, the fire season last year was the worst on record in terms of the number of fires and acres burned. There were 96. 385 fires and 9.873429 acres affected by fire in a year that was 125% more destructive(毁灭性的) than the10-year average. These fires cost the federal government $1.5 billion to fight, and this figure does not include the money spent by local and state governments as part of the effort.
Fires in the southern states represented half of the national total last year with Texas, Oklahoma and Arkansas being home to a usually high amount of activity. Wildfire has also taken place in Western states such as California, Colorado and Alaska throughout the past 10 years.
It is said that two-thirds of forest fires are started accidentally by people. Almost one quarter are purposely set, while lighting causes 10%.
Forest fires can have advantageous effects. Charcoal(木炭) enriches soil and some plant species(种类) grow well after fire. The cones of the jack pine tree, for example, will not spread their seeds unless there is heat. Douglas fir trees grow best in open sunlight areas after fire.
1.Forest fires are considered to be the most frightening because____.
A. fire-retardant chemicals can't be made use of
B. huge walls of flames can burn acres of land
C. they make the greatest loss of all disasters
D. they spread too fast and do great damage
2.Almost 25% forest fires are set_____.
A. unexpectedly B. by lighting C. on purpose D. naturally
3.What does the last paragraph mainly talk about?
A. The advantages of forest fires. B. The usage of charcoals.
C. Pine trees need fires. D. Fires destroy all plants but two.
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First impressions are the most lasting. After all, you never get ______second chance to make ______ first impression.
A. a; the B. the; the C. a; a D. the; a
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First impressions are the most lasting. After all, you never get ______ second chance to make _______ first impression.
A. a; the B. the; the C. a; a D. the; a
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There are some injuries that are common to all types of extreme sports. The following are some of the important things to do to prevent extreme sports injuries. 1. But they can definitely minimize the risk of injuries.
Warm up.
2. They include a combination of cardiovascular(心脏血管的)exercises, strength drills and stretching. Cardiovascular exercises increase body temperature, heart rate and blood circulation, which is required for further movement of the body. Strength drills increase the stamina of the body, while stretching warms up the muscles preparing them for sudden forceful movements. 3. It also plays an important role in boosting the team spirit for a team sport. A warm-up session should last for at least 20 minutes and it can extend up to half an hour.
Avoid overworking.
There are some people who do not exercise their body for the sport on a regular basis and perform a week's task in a day or two. 4. They do not realize the effect of overworking during the performance and keep doing it until they feel extremely tired. Apart from the actual sport, one should also avoid overdoing the warm-up exercises before the activity.
5.
Just as warming up is essential before any rigorous(充满活力的) physical activity, cooling down the body after playing a rigorous sport is also a significant part of physical conditioning. When you are done with your sports session, you can conclude with some walking, jogging or light running. Slight stretching exercises, focusing on specific muscles, will also be useful for cooling down the body.
A. Cool yourself down.
B. Look for a coach to train you.
C. These people are likely to suffer from extreme sport injuries.
D. However, there are no perfect methods which can assure you 100% safety.
E. Along with physical preparation, warming up prepares you mentally to begin a sport.
F. You should also be careful about your clothing selection for warmth and protection.
G. Warm-up exercises are very important before you begin any sports practice.
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_________all of them are strong candidates, only one will be chosen for the post.
A. Since B. As C. If D. While
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Hummingbirds (蜂鸟) are one of nature’s most energetic fliers and the only birds to hover in the air by relying on their strength alone.
Now scientists have found that it is the ratio (比值) of the bird’s wing length to its width that makes them so efficient. The discovery is helping experts compete with 42 million years of natural selection to build helicopters that are increasingly efficient.
David Lentink, an assistant professor at Stanford University in California, tested wings from 12 different species of hummingbirds, which he sourced from museums. He placed them on a machine used to test the aerodynamics (气力学) of the helicopter blades (桨叶). Professor Lentink’s team used the same machine to test the blades from an advanced micro-helicopter used by the UK’s army. They found that the micro-helicopter’s blades are as efficient at hovering as the average hummingbirds.
But while the micro-helicopter’s blades kept pace with the average hummingbird wings, they could not keep up with the most efficient hummingbird’s wing. The wings of Anna’s hummingbird were found to be about 27 percent more efficient than the man-made micro- helicopter’s blades.
While Professor Lentink wasn’t surprised at nature’s superiority, he said that helicopter blades have come a long way. “The technology is at the level of an average hummingbird,” he said. “A helicopter is really the most efficient hovering device that we can build. The best hummingbirds are still better, but I think it’s amazing that we’re getting closer. It’s not easy to match their performance, but if we build better wings with better shapes, we might match hummingbirds.”
Professor Lentink said that we don’t know how hummingbirds maintain their flight in a strong wind, how they navigate (确定方向) through branches, or how they change direction so quickly. He thinks that great steps could be made by studying wing aspect ratios—the ratio of wing length to wing width. Understanding these abilities and characteristics could be a benefit for robotics and will be the focus of future experiments.
1.What did the scientists find about hummingbirds?
A. Their wings are long and wide.
B. They can hover in the air for a long time.
C. The ratio of their wing length to wing width is very important.
D. They are the most energetic flier in nature.
2.Which is the right order of Professor Lentink’s research?
① Tested wings from different species of hummingbirds.
② Got resources from museums.
③ Analyzed the results and drew a conclusion.
④ Tested the blades from a micro-helicopter.
A. ①②③④ B. ②①③④ C. ②④①③ D. ②①④③
3.According to Professor Lentink, what will be the focus of future experiments?
A. To know how hummingbirds can fly in a strong wind.
B. To know how hummingbirds change direction so quickly.
C. To develop a new kind of helicopter.
D. To study the secrets of hummingbirds.