Big trees are incredibly important ecologically. For a start, they provide food for countless other species and shelter for many animals. With their tall branches in the sun, they capture vast amounts of energy. This allows them to produce massive crops of fruit and flowers that sustain much of the animal life in the forest.
Only a small number of tree species have the genetic ability to grow really big. The biggest are native to North America, but big trees grow all over the globe, from the tropics to the forests of the high latitudes (纬度). To achieve giant size, a tree needs three things: the right place to establish its seedling, good growing conditions and lots of time with low adult death rate. Lose any of these, and you will lose your biggest trees.
In some parts of the world, populations of big trees are dwindling(逐渐变少) because their seedlings cannot survive. In southern India, for instance, an aggressive non-native bush, Lantana camara, is invading the floor of many forests. Lantana grows so thickly that young trees often fail to take root. With no young trees to replace them, it is only a matter of time before most of the big trees disappear.
Without the right growing conditions, trees cannot get really big and there is some evidence to suggest tree growth could slow in a warmer world, particularly in environments that are already warm. Having worked for decades at La Selva Biological Station in Puerto Viejo de Sarapiqui, Costa Rica, David and Deborah Clark and colleagues have shown that tree growth there declines markedly in warmer years. “During the day, their growth shuts down when it gets too warm, and at night they consume more energy because their metabolic (新陈代谢) rate increases,” explains David Clark. With less energy produced in warmer years and more being consumed just to survive, there is even less energy available for growth.
The darks’ theory, if correct, means tropical forests would shrink over time. The largest, oldest trees would progressively die off and tend not to be replaced. According to the Clarks, this might cause a destabilization(不稳定) of the climate; as older trees die, forests would release some of their stored carbon into the atmosphere, causing a cycle of further warming, forest shrinkage and carbon emissions.
Besides, big trees face threats from elsewhere.According to the passage, big trees make great contributions to the ecosystem because .
| A．they can capture large amounts of energy. |
| B．they determine the change of global climate. |
| C．they provide the essentials for many creatures. |
| D．they can avoid a new cycle of further warming. |
All the following factors are a must for making big trees EXCEPT .
| A．no deadly damage |
| B．genetic contribution |
| C．ideal environment for growth |
| D．high-latitude location |
What is the best title of the passage?
| A．Big trees in trouble. |
| B．Advantages of big trees. |
| C．Results of big trees’ disappearing. |
| D．Importance of big trees to humans. |
What will the author most probably discuss after the last paragraph?
| A．More threats to the existence of big trees. |
| B．The effect of human activities on big trees. |
| C．Benefits of big trees to the whole atmosphere. |
| D．Comparison between common trees and big ones. |
A student walks into his first class and realizes he forgot all about the midterm exam. He knows he needs to bring his grades up, and getting a zero will make it nearly impossible. He quickly jots down some notes and shoves them under his lap hoping it will help him pass. Cheating is a major concern in all academic environments. Students are creating new and more outrageous(令人吃惊的) ways of cheating every day; some claim that certain accounts of cheating can be justified, but overall it can always be prevented.
Cheating has been around forever, and millions of ways to cheat have been fashioned. Copying homework and cheat sheets are some of the most basic ways students in all education levels have cheated. Some students think nothing about writing a few answers on their hand, in a gum wrapper, or boldly using a study guide to cheat. Desperate students have even gone as far as to steal the test or scan in bottle wrappers and put answers into the nutrition label. The internet has now become available in almost every location. Computers can be accessed at school, at home, and now even on cell phones. This opens a doorway for even more methods of cheating to be born.
There are countless opinions on whether or not cheating can be justified. The truth is this behavior will always be a matter of opinion with each scenario of cheating. Students often rationalize their cheating by claiming they forgot to look over the material or did not understand what the teacher or professor was saying. Some may counter these arguments by saying that the student could have set reminders or asked the teacher to explain the material before the day of the test. Some other reasons students believe cheating is justified are their heavy workloads and trying to find time for school, sports, friends, and family. This may be true in certain instances, however, all students have these problems, and it is unfair to the students refrain(制止) from cheating when the student who is dishonest receives a better grade. The majority of students who think cheating is acceptable may believe the reason for this is that sometimes students are unaware they are cheating, there is not enough time given for assignments, or that the information is too much for the course.
It may be difficult to accomplish, but cheating can be prevented. Teachers and professors have tried many options to stop cheating. These options can range anywhere from simply spreading test-takers out in a room, to expelling(驱逐) a student, which will most likely hindertheir plans of getting into another college. One simple way to fix the problem is to scold the student when caught. They may be so scared or embarrassed that they never do it again. This is a risky way to prevent cheating in some cases, however, because it can possibly damage self-esteem. Another simple way to avoid cheating is to create many different kinds of the same test. This prohibits students from getting the answers off of a neighbor's test, but students still have the option of using other cheating tactics.
There may be a million ways to cheat and get away with it, but there are few times, if any, that it is justified. Cheating never has to be a necessity and is never worth compromising morals and losing years worth of working towards a degree. This problem is spreading throughout America; with everyone's help, it can be stopped.Which is the best title of this passage?
| A．To cheat or not to cheat | B．Show your opinion on cheating |
| C．Debates on cheating | D．Different ways of cheating |
The second paragraph mainly tells us that ________.
| A．cheating through the Internet is the most basic way |
| B．students who cheat in exams are cleverer |
| C．millions of ways to cheat have been fashioned |
| D．students cheat in exams to score better grades |
The reason that is given by most students who think cheating is understandable is that ________.
| A．they don’t understand their teachers’ words |
| B．they bury themselves in a lot of homework |
| C．they don’t have enough time to complete the study tasks |
| D．they forget to look over the material |
What is the disadvantage of scolding the cheating students according to the passage?
| A．They may continue to cheat next time. |
| B．They may be hurt mentally. |
| C．They may use other cheating tactics. |
| D．They may get on badly with their teachers. |
What is the author’s attitude towards cheating?
| A．It is reasonable | B．It is necessary |
| C．it can be praised | D．It must be prevented |
Common sense would tell us that physically active children may be more likely to become active and healthy adults.
In the United States, elementary and middle schools are advised to give students two and a half hours of physical activity a week. That is what the Centers for Disease Control and Prevention and the American Heart Association recommend. They say high schools should provide about four hours of physical activity each week.
Yet many schools across the country have reduced their physical education programs. Just this week, a study reported that lifeexpectancy has fallen or is no longer increasing in some parts of the United States. The situation is worst among poor people in the southern states, and especially women. Public health researchers say it is largely the result of increases in fatness, smoking and high blood pressure. They also blame differences in health services around the country.
In 2006, a study found that only four percent of primary schools provided daily physical education all year for all grades. This was true of eight percent of middle schools and two percent of high schools. The study also found that twenty-two percent of all schools did not require students to take any P.E.
Charlene Burgeson , a health expert says one problem for P.E. teachers is that schools are under pressure to put more time into academic subjects. Also, parents may agree that children need exercise in school. Yet many parents today still have bad memories of being chosen last for teams because teachers favored the good athletes in class.
But experts say P.E. classes have changed. They say the goal has moved away from competition and toward personal performance, as a way to build a lifetime of activity. These days, teachers often lead activities like weight training and yoga.
Some parents like the idea of avoiding competitive sports in P.E. class. Yet others surely dislike that idea. In the end, schools may find themselves in a no-win situation.The underlined word “expectancy” in Paragraph 3 probably means “ ”
| A．quality | B．length | C．exception | D．depth |
According to the passage which of the following may not lead to poor health?
| A．Fatness. | B．Smoking | C．High blood pressure. | D．Health service |
What can be inferred after you read this passage?
| A．Physical activities are becoming more and more popular in American schools. |
| B．All the schools provided daily physical education all year for all students. |
| C．Parents think children need physical education for their bad memories. |
| D．Students spent less time on physical education for academic pressure. |
What is the main idea about this passage?
| A．P.E. is the most important subject for all students. |
| B．P.E has changed its goal for some reasons in America. |
| C．It introduces us the present situation of P.E in American schools and its cause. |
| D．P.E can help students improve their academic subjects. |
President Obama: I want to welcome Vice President Xi to the Oval Office and welcome him to the United States. This is obviously a great opportunity for us to build on the U. S.-China relationship, but also an opportunity to return the extraordinary hospitality that Vice President Xi showed Vice President Biden during his recent visit to China.
As I indicated during my recent visit to APEC and the East Asia Summit, the United States is a Pacific nation. And we are very interested and very focused on continuing to strengthen our relationships, to enhance our trade and our commerce, and make sure that we are a strong and effective partner with the Asia Pacific region. And obviously, in order to do that, it is absolutely vital that we have a strong relationship with China.
So, Mr. Vice President, I hope you have a wonderful visit while you're here. I'm sure the American people welcome you. I'm glad that you're going to get an opportunity to get out of Washington. I know you'll be visiting Lowa, which you visited many years ago when you were governor. And I understand you're also going to Los Angeles and maybe even taking in (观看) a Lakers basketball game. So I hope you enjoy that very much.
I want to extend my deepest welcome to you, and look forward to a future of improved dialogue and increased cooperation in the years to come.Where can you most probably read the passage?
| A．In a science report. | B．In a news report. |
| C．In a guidebook. | D．In an advertisement. |
Which is true according to the passage?
| A．Biden once paid a visit to China before this talk. |
| B．Obama didn't attend APEC or the East Asia Summit recently. |
| C．Biden and Xi Jinping are holding the talk in the Oval Office of the White House. |
| D．The talk is being held between China and the USA in the Oval Office of New York. |
From Para. 3, we can learn that Vice President Xi ____.
| A．will visit New York, Washington DC and Los Angeles |
| B．will go to Los Angeles to watch a soccer game |
| C．visited Lowa many years ago, when he was governor |
| D．visited Lowa many years ago, when he was a vice president |
Jeremy Shu-How Lin, who was born in California, 1988, world-famous now，is the first Chinese-American professional basketball player with the New York Knicks of NBA.
It hasn't been an easy road for Lin. After high school, Lin sent his resume(简历) and a DVD of highlights to all the Ivy League schools, and his dream schools Stanford and UCLA. Harvard and Brown were the only schools that guaranteed him a spot on their basketball teams, but Ivy League schools do not offer athletic scholarships.
After graduating from Harvard University, Lin went undrafted in the 2010 NBA Draft . Lin spent his first season with his hometown the Golden State Warriors. He saw limited minutes with the Warriors, but was cheered in arenas(比赛场) around the country, particularly in cities with large Asian communities, as fans came out in crowds to cheer their homegrown star. In late 2011, Lin spent less than two weeks with the Houston Rockets, moving to the New York Knicks at the very end of the year.
He has made several trips to the NBA's Development League, a minor league for players who show promise but need seasoning before they can compete at the highest level. It appears to have paid off. In February 2012, after keying the Knicks victory over New Jersey, Lin was named the starter for the Utah game, a position he appears to have a hold on in the short term, as Baron Davis, who signed in December to play the position, stays on the disabled list. Lin will likely get stronger the more minutes he plays, and even if Davis returns, spelling the older, recovering player could be productive for Lin: a proven good student who can learn a lot from practicing against a veteran.
Without the services of All-Stars Carmelo and Amare, Lin led New York to a 4-0 record last week. He became the first player in NBA history to record at least 20 points and seven assists in each of his first four starts, which generated a global following known as Linsanity. The Associated Press called Lin "the most Surprising story in the NBA".From the passage we can know that Lin．
| A．enjoyed himself in the Houston Rockets |
| B．used to be a leader in the New York Knicks |
| C．is a proven good student who can learn a lot from other players. |
| D．led New York to success with the help of some All- Stars. |
According to the passage, which statement is true?
| A．Harvard offered Lin an athletic scholarship． |
| B．Harvard and Brown make sure of Lin's position on their basketball teams． |
| C．Stanford and Harvard were Lin's dream schools． |
| D．Lin’s DVD impressed all the Ivy League schools greatly． |
Which of the following can be the main idea of this text?
| A．How the word Linsanity came into being． | B．Introduction to Jeremy Shu-How Lin． |
| C．How Lin becomes successful． | D．Lin and New York Knicks |
Some years ago industries had more freedom than they have now, and they did not need to be as careful as they must today. They did not need to worry a lot about the safety of the new products that they developed. They did not have to pay much attention to the health and safety of the people who worked for them. Often new products were dangerous for the people who used them; often conditions in the work place had very bad effects on the health of the workers.
Of course sometimes there were real disasters which attracted the attention of governments and which showed the need for changes. Also scientists who were doing research into the health of workers sometimes produced information which governments could not ignore. At such times, they inquire into the causes of the disasters or the problems. New safety rules were often introduced as a result of these inquiries; however. the new rules came too late to protect the people who died or who became seriously ill.
Today many governments have special departments which protect customers and workers．In the U.S, for example, there is a department which tests new airplanes and gives warnings about possible problems. It also makes the rules that aircraft producers must follow. Another department controls the foods and drugs that companies sell. A third department looks at the places where people work. and then reports any companies that are breaking the laws which protect the health and safety of workers. Of course, new government departments and new laws cannot prevent every accident or illness. but they are having some good results. Our work places are safer and cleaner than before. The planes and cars which we use for travel are better. Producers are thinking more about the safety and health of the people who buy and use their products. The main topic of the passage is ___________________________________________.
| A．conditions in the work place | B．the freedom of industries in the past |
| C．changes in industrial production | D．the safety and health of workers and customers |
It can be inferred from the passage that in the past __________________________.
| A．workers often got ill because of the poor working conditions |
| B．companies were free to put out any products they wanted to |
| C．many people were killed by dangerous products |
| D．industries were as careful in management as they are today |
It is implied (暗示) in the passage that ________________________________________.
| A．governments and companies had different opinions about the safety of products |
| B．governments paid little attention to the safety of products |
| C．government officials often did not listen to scientists |
| D．in the past no safety laws were introduced by governments |