1. Passage Twenty-SevenOut of all the students who enroll in a massive open online course (MOOC)， only about 5 percent complete the course and receive a certificate of accomplishment.This statistic is often cited as evidence that MOOCs are fatally flawed (有缺陷的)and offer little educational value to most students.Yet more than 80 percent of students who fill out a post-course survey say they met their primary objective.How do we look at these two facts? We’re used to focusing on completion rates in higher education， but they’re not the only—or even the most meaningful—indicator of engagement in open online courses.With no cost to enroll， no punishment for dropping out， and little reward for actually earning a certificate， MOOCs are fundamentally different from traditional classes—and students use them in fundamentally different ways.Data from more than 1.8 million students enrolled in 36 MOOCs offered by the University of Pennsylvania show that students treat MOOCs like a buffet (自助餐)， sampling the material according to their interests and career goals.Some are curious about the subject matter and just watch one or two video lectures; others use the discussion forums to connect with their intellectual peers around the world.Of all enrolled students， nearly 60 percent watch at least one video， complete at least one assignment， or post at least once in a forum.So focusing on the tiny fraction of students who complete a MOOC is misguided.The more important number is the 60 percent engagement rate.Students may not finish a MOOC with a certificate of accomplishment， but the courses nonetheless meet the educational goals of millions.What do we learn about MOOCs from Para.1?

6、The pollution of groundwater by nitrates(硝酸盐)is of concern to public health authorities and environmental organizations because high nitrate concentration(高硝酸含量)s in drinking water can cause methaemoglobinaemia(高铁血红蛋白血)in infants.Another environmental problem associated with high nitrate concentration in groundwater is eutrophication(富营养化)of receiving waters(供水).Virtually all decisions about the control of nitrate pollution of ground water are made in the face of uncertainties that frustrate(阻止，挫败)efforts to guarantee the desired results.The decisions also have to be made in an adversarial(意见相左，敌对不可调和的)environment in which the goals of society and those of the agricultural sector(农业部门)are often different.

31.The conference ()a full week by the time it ends.

A. 　must have lasted

B. 　will have lasted

C. 　would last

D. 　has lasted

3. Passage SeventeenNo one knows how man learned to make words.Perhaps he began by making sounds like those made by animals.Perhaps he grunted like a pig when he lifted something heavy.Perhaps he made sounds like those he heard all round him——water splashing， bees humming， a stone falling to the ground.Somehow， he learned to make words.As the centuries went by， he made more and more new words.This is what we mean by language.People living in different countries made different kinds of words.Today there are about fifteen hundred different languages in the world.Each contains many thousands of words.A very large English dictionary， for example， contains four or five hundred thousand words.But we do not need all these.Only a few thousand words are used in everyday life.The words you know are called your vocabulary.You should try to make your vocabulary bigger.You’re supposed to read as many books as you can.There are plenty of books written in easy English for you to read.You will enjoy them.When you meet a new word， you should find it in your dictionary.Your dictionary is your most useful book.People from different countries ().

50.The output of new energy vehicle this year is ()last year.

A. 　as much as twice

B. 　as twice much as

C. 　twice as much as

D. 　twice so much as

49.They had to put ()the meeting due to the ongoing COVID-19.

A. 　forward

B. 　up

C. 　down

D. 　off

41.A hobby is something that you never get tired of—the more time you devote to it， the more fun you will have.

3. Passage Twenty-TwoThough some people have suggested that women should return to housework in order to leave more jobs for men， the idea has been rejected by both women and men in public opinion polls (民意测验).Lately some union officials have suggested that too many women are employed in type of work more suitable for men and that women should step aside to make way for unemployed young men.They argue that women—especially women in their childbearing years actually delay economic development and result in lower productivity， poor quality and inefficiency.To solve the problem， they have suggested that the working women stay at home while their husbands or brothers were given double wages.They argue that under these circumstances， families would retain their same level of income， and women could run the house and raise children much better.The suggestion has been rejected by 9 out of 10 people polled.A hundred persons in a big city were questioned last summer.Out of 50 women， 46 said they were unwilling to leave their jobs， no matter what the situation was.The other 4 said they would like to return home if their jobs could be taken by their sons or daughters.Of 50 men polled， only 6 said they would like to see their wives give up their jobs， if it meant higher wages for themselves.Some other people have suggested another way called “phased employment theory”.The theory suggests that a woman worker take leave from her job when she is seven months pregnant (妊娠)and stay off the job until her baby reaches the age of 3.It suggests that women on leave receive 75 percent of their normal salary and be allowed to return to work after the 3-year period.This will benefit children， women， their families and the society.Some of those polled， both women and men， felt the idea is a good one.It definitely seems to be more acceptable than the suggestion that women return to home forever.According to the passage， the suggestion that women should return to housework was ().

7.Our son doesn＇t know what to()at the university; he can＇t make up his mind about his
future.

A. 　take in

B. 　take up

C. 　take over

D. 　take after

5. Passage FifteenBig data can be defined as information that is too big or complex to be contained or processed by any one machine or person.As a student at the University of Sussex， Julian Dailly had two majors——English and philosophy.When he completed his studies， Dailly wondered how he would ever earn a living in a world filled with machines and technology.Now， he is part of the big data industry that includes Google and Facebook.Dailly’s research company， Monar Consulting， started three years ago with five employees.The company’s earnings have increased by 25% each year.It now employs 90 people.“What we do here is we try to discover what’s meaningful for people and link that to their economic behavior，” Dailly said.He noted the importance of working with people with different skills.“We have people from traditional research backgrounds， in addition to some in social sciences， economics， people from tech backgrounds， and sales people，” Dailly said.Companies like Dailly’s employ recent college graduates.The industry profits from the ideas of these young men and women.New forms of data also make it possible for some observers to predict the future.They are more valuable to companies than the traditional forms of data recording or reporting.“We have access to the core information inside people’s heads，” Dailly said， “They tell you what people are going to do as opposed to what they’ve done.That helps people take proper action in advance.This makes it much more useful for strategy.”Julian Dailly dismisses concerns that computers have finally taken control of our daily lives.“Some may worry that humans will be allowed to be replaced by machines.I think it’s a fantasy.”According to Dailly， the idea that humans may be replaced by machines ().

5. Passage ElevenDoctors say anger can be an extremely damaging emotion， unless you learn how to deal with it.They warn that anger can lead to heart disease， stomach problems， headaches， emotional problems and breast cancer.Anger is a normal emotion that we all feel from time to time.Some people express anger openly in a calm and reasonable way.Others burst with anger， screaming and yelling.But still others keep their anger inside.They cannot or will not express it.This is called (repressing)anger.For years some doctors claim that both repressing and expressing anger can be dangerous.They say that in both situations the brain of an angry person releases the same hormones (荷尔蒙).They spend the heart rate， raise blood pressure or sugar level in the blood.As a result， the angry person feels excited and is ready to react.The violent reaction may lead to high blood pressure.However， some other doctors argue that repressing anger is more dangerous to a person’s health than expressing it.They believe that those who keep their anger inside may face a greater danger of heart disease.Most doctors agree that it is important to learn how to deal with anger.They say the first step is to admit that you are angry and recognize the real cause of the anger， then decide if the cause is serious enough to get angry about.If so， you should not express your anger immediately and try to wait until your anger has cooled down， so that you are able to express yourself calmly and reasonably.They also believe that a good way to deal with anger is to find humor in the situation that has made you angry.After all， it is much healthier to laugh than to get angry.What is the tone of this passage?