第4部分：阅读理解（第31~45题，每题3分，共45分）

下面有3篇短文，每篇短文后有5道题，每题后面有4个选项。请仔细阅读短文并根据短文回答其后面的问题，从4个选项中选择1个最佳答案涂在答题卡相应的位置上。

第一篇 A New Finding

British cancer researchers have found that childhood leukaemia is caused by an infection and clusters of cases around industrial sites are the result of population mixing that increases exposure. The research published in the British Journal of Cancer backs up a 1988 theory that some as yet unidentified infection caused leukaemia-not the environmental factors widely blamed for the disease.

"Childhood leukaemia appears to be an unusual result of a common infection," said Sir Richard Doll, an internationally-known cancer expert who first linked tobacco with lung cancer in 1950. "A virus is the most likely explanation. You would get an increased risk of it if you suddenly put a lot of people from large towns in a rural area, where you might have peopie who had not been exposed to the infection." Doll was commenting on the new findings by researchers at Newcastle University, which focused on a cluster of leukaemia cases around the Sellafield nuclear reprocessing plant in Cumbria in northern England. Scientists have been trying to establish why there was more leukaemia in children around the Sellafield area, but have failed to establish a link with radiation or pollution. The Newcastle University research by Heather Dickinson and Louise Parker showed the cluster of cases could have been predicted because of the amount of population mixing going on in the area, as large numbers of con- struction workers and nuclear staff moved into a rural setting. "Our study shows that population mixing can account for the, (Sellafield) leukaemia cluster and that all children, whether their parents are incomers or locals, are at a higher risk if they are born in an area of high population mixing," Dickinson said in a statement issued by the Cancer Research Campaign, which publishes the British Journal of Cancer.

Their paper adds crucial weight to the l988 theory put forward by Leo Kinlen, a cancer epidemiologist at Oxford University, who said that exposure to a common unidentified infection through population mixing resulted in the disease.

31 Who first hinted at the possible cause of childhood leukaemia by infection? ________

A Leo Kinlen.

B Richard Doll.

C Louise Parker.

D Heather Dickinson.

32 Which statement can be supported by Heather Dickinson and Louise Parker's new findings? ________

A Radiation has contributed to the disease.

B Putting a lot of people from rural area in a large towns increases the risk of childhood leukaemia.

C Population mixing is the most important reason for leukaemia cluster.

D Childhood leukaemia is caused by an unusual infection.

33 According to the passage, which of the following is true? ________

A Most people believe childhood leukaemia is due to environmental factors.

B Population mixing best explains the cause of childhood leukaemia.

C Radiation has nothing to do with childhood leukaemia.

D Children born in a large town are at higher risk of leukaemia.

34 Cancer Research Campaign is most possibly a ________.

A medical journal

B research institute

C private company

D governmental agency

35 This passage is mainly about ________.

A the cluster of leukaemia eases around the Sellafield nuclear reprocessing part

B the kind of infection that causes childhood leukaemia

C the causes of childhood leukaemia

D a new finding by British scientists