____some doubt among scientists about the cause of cancer.


  1. A.
    It exists
  2. B.
    There exists
  3. C.
    There is existing
  4. D.
    It is existing
B
考查特殊句式。There be結(jié)構(gòu)中的系動(dòng)詞換成其它的系動(dòng)詞如exist, happen，seem等；系動(dòng)詞是沒(méi)有進(jìn)行時(shí)的。所以排除CD。句意：在科學(xué)家中對(duì)于癌癥的原因存在著一些懷疑和爭(zhēng)論。
練習(xí)冊(cè)系列答案
相關(guān)習(xí)題

科目：高中英語(yǔ) 來(lái)源：2013-2014學(xué)年河北省高三上學(xué)期四調(diào)考試英語(yǔ)試卷（解析版） 題型：閱讀理解

It is often said that man has become the enemy of our planet. This is no exaggeration(夸張), for reports show that man’s greed has done much to destroy the earth. Man, in his greedy desire for financial growth, has polluted the air, land and water, and has robbed our valuable natural resources. Man’s industrial plants pour out poisonous waste that pollutes the sea and puts life in the sea under the threat of dying out; at the same time, they release alarming amounts of carbon dioxide, chlorofluorocarbons (CFCs) and other pollutants. Small wonder that the air now is much warmer and more impure than ever before.

Of course, this is not just because of man’s greed—it is man’s pressing need as well. For instance, in developing countries, huge financial foreign debts have forced governments to approve the cutting of forests for agriculture or ranching. As a result, forests are cut down just to meet man’s immediate needs.

Perhaps unknowingly，man has changed the make-up of the earth's atmosphere. Scientific studies have shown that CFCs used in refrigerators and industrial cleaners are fast destroying the ozone layer—a protective layer in the atmosphere that protects us against the harmful effects of the sun’s ultraviolet (紫外線)rays. In fact, documented reports have shown a terrible fact that there are “holes” in the ozone layer over the Antarctic. And they appear to be expanding.

Faced with these environmental problems, world leaders have shown deep concern. The UN Environmental Programme (UNEP) has arranged international agreements like the Vienna convention of 1985 and the Montreal Protocol of 1989 to preserve the ozone layer by controlling the production, use and trade of destructive chemicals.

There may be some doubt as to how effectual these agreements may be, given that some countries still maintain an “I-don’t-care” attitude. Their attitude is probably due to their failure to grasp the importance of the problem. Then, there is no doubt that environmental education on an international scale（規(guī)模）is greatly needed, so that all countries, great and small—the “haves” and the “have nots”—may realize their responsibilities for our planet.

In the meantime, the UNEP seems to have taken steps in the right direction, and it is hoped that in the not so distant future, all nations of the world will join hands in saving mother earth.

1.Which of the following is a reason for the cutting and burning of forests?

A. To build houses for more population.            B. To have land for agriculture.

C. To export trees to other countries.                           D. To build industrial plants. 

2.The holes in the ozone layer are largely due to________.

A. man’s research activities                                     B. the greenhouse effect

C. the ultraviolent                                                      D. harmful chemicals

3.Why don’t some countries care about the problem of the environment?

A. They don’t want to put their lives in danger.

B. They just don’t know how to solve the problem.

C. They haven’t realized the seriousness of the problem.

D. They don’t want to break their international commitment.

4.66. What is the author’s attitude towards the future of the environment?

A. Hopeful.                         B. Unconcerned                 C. Doubtful                          D. Objective

 

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2014屆湖北武漢市高二上學(xué)期期末考試英語(yǔ)試卷（解析版） 題型：閱讀理解

Television will turn 86 years old on September 7, 2013, and it has never looked better. In its youth, television was a piece of furniture with a tiny, round screen showing unclear pictures of  low­budget programs. In spite of its shortcomings, it became well-received. Between 1950 and 1963, the number of American families with a television jumped from 9% to 92% of the population.

As the audience got larger, the technology got better. Television sets became more reliable through the 1960s. Both of the reception and the picture improved. The major networks started broadcasting programs in color.

Even greater improvements were coming according to Sanford Brown, who wrote an article for the Post in 1967. Surprisingly, just about every prediction he made in the article became a reality. For example: All sets in the not­distant future will be color instruments. He also predicted that TV sets would become smaller, simpler, more reliable and less expensive and may forever put the TV repairman out of work. Smaller sets do not, of course, mean smaller screens. TV engineers expect screens to get much bigger. However, today's 3­D TV is even farther away, if it's coming at all.  There is some doubt whether the public would be eager to pay for it, in view of people's cold reception given to 3­D movies.

But the technology with the greatest potential, according to Brown, was cable television (有線電視), which was still in its early stages then. As he predicted, the future of cable television was highly interactive. It wasn't cable television that gave Americans their electronic connection to the world, however. It was the Internet.  He even foresaw the future office: using picture phones, big­screen televisions for conferences, and computers providing information, at the touch of a button.

Brown ever said, “The future of television is no longer a question of what we can invent. It's a question of what we want.”

1.What can we infer about television sets in the 1960s?

A．They were very popular with Americans.

B．Their appearance remained unchangeable.

C．They showed black­and­white pictures.

D．Their pictures were of poor quality.

2.Which of the followings did Sanford Brown fail to predict?

A．Television's good quality.

B．The invention of 3­D TV.

C．The more functions of TV.

D．The potential of cable TV.

3.From the passage we know _________.

A．TV will certainly take the place of computers

B．There won’t be further improvement on TV

C．TV repairmen will be out of work in the future

D．3­D movies don’t appeal to people very much

4.What is the text mainly about?

A．The shortcomings of television.

B．The advantages of television.

C．The development of television.

D．The invention of television.

 

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：西藏拉薩中學(xué)2009-2010學(xué)年高二第二次月考試題（英語(yǔ)） 題型：單項(xiàng)填空

There is still some doubt ________ the autumn sports meet will be held in our school, but there is no doubt ________ it will be held soon after our National Day holiday.

A．that; that

B．whether; whether

C．that; whether

D．whether; that

 

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：單項(xiàng)選擇2 題型：單項(xiàng)填空

There is some doubt ____ the sick schoolboy can join in the English evening party on Sunday.

A. /    B. whether  C. that           D. which

 

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：20102011學(xué)年度江西省高二第一學(xué)期期末英語(yǔ)試卷 題型：單項(xiàng)選擇題

There is some doubt _________ Mr Zhang will sign the contract with us.

A. when      B. whether C. if        D. that

 

查看答案和解析>>

同步練習(xí)冊(cè)答案