单选题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 people 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 mount of population mixing going on in the area, as large numbers of construction 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 newcomers 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 1988 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.

单选题He ______ outrage by calling the TV programmes "talking wallpaper". A. provoked B. evoked C. revoked D. invoked

单选题The car one drives may show his/her______or social position.

单选题In a coal-mining area, the land tends to______causing damage to roads and buildings.

单选题______ a ticket for the match, he can now only watch it on TV at home.

单选题Although the family trusted her, she let them ______badly.

单选题The problem is that most local authorities lack the ______ to deal sensibly in this market. A. anticipation B. perception C. prospect D. expertise

单选题The nuclear family ______ a self-contained, self-satisfying unit composed of father, mother and children.

单选题Which group of people make some efforts to help pupils in elementary schools?

单选题The Bureau of Public Security has decided to hold an {{U}}inquiry{{/U}} to find out the cause of the big fire.

单选题Already the class is ______ about who our new teacher will be. [A] foreseeing [B] contemplating [C] speculating [D] fabricating

单选题He intends to______the secretary he has dismissed by a less glamorous but more efficient one.

单选题I regret to say that your thesis requires more thinking than ______ for the problem is exceedingly complex.

单选题I'm sorry to ______ you while you are working, but I must ask you a question about English.

单选题When A putting B in historical perspective , from the time of Franklin Roosevelt's New Deal to C the present , the D fallen status of government as a protector and benefactor is extraordinary.

单选题If you can convince the interviewer of your special qualifications, your chance of being accepted will be greatly {{U}}enhanced{{/U}}.

单选题Sometimes a dictionary designates a noun as attributive, which means that it can be used to describe another noun or name its attributes.(2003年春季电子科技大学考博试题)