试题与答案

长为L粗细均匀的圆柱体,其轴线与直角坐标系x轴重合,底面过原点且与yOz平面平行

题型:选择题

题目:

长为L粗细均匀的圆柱体,其轴线与直角坐标系x轴重合,底面过原点且与yOz平面平行,如图所示,圆柱体在yOz平面内质量均匀分布,在x方向密度均匀增加,则圆柱体重心位置坐标(xc,yc,zc)为(  )

A.yc=0,,zc=0,xc

B.yc=0,,zc=0,xc=

C.yc=0,,zc=0,xc

D.无法判断

答案:

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题型:阅读理解

Why do some people flush when they drink alcohol? This effect is a common reaction to alcohol among East Asians. It affects about 36 percent of Japanese, Chinese and Koreans.

For many, even a small amount of alcohol can cause unpleasant effects. Most commonly, their face, neck and sometimes their whole body turn red. People might also feel uncomfortable and sick to their stomach. They might experience a burning sensation, increased heart rate, shortness of breath and headaches.

The cause is a genetic difference that they are born with called an ALDH2 deficiency (缺乏). It prevents their bodies from treating alcohol the way other people do. But the effects might be more serious than just a red face. Researchers warn of a link between this condition and an increased risk of cancer of the esophagus (食道) from drinking alcohol.

The more alcohol people with this deficiency drink, the greater their risk is. In Japan and South Korea, for example, many people have the deficiency but still drink heavily. Researchers found that these drinkers develop a form of esophageal cancer six to ten times more often than those without the deficiency.

Esophageal cancer is one of the deadliest cancers. It can be treated when found early, but once it grows the chances of survival drop sharply. The researchers estimate that at least five hundred forty million people have the deficiency, about eight percent of the world’s population.

Philip Brooks is a researcher at the National Institute in the United States. He says it is important to educate people about the link between the alcohol flushing effect and esophageal cancer. He says doctors should ask East Asian patients about their experiences with facial flushing after drinking alcohol. Those with a history of it should be advised to limit their alcohol use. They should also be warned that cigarette smoking works with the alcohol in a way that further increases the risk of esophageal cancer.

小题1:The underlined word “flush” in Paragraph 1 probably means “_________”.

A.walk unsteadily

B.appear unpleasant

C.turn red in the face

D.talk more than usual小题2:The second paragraph is mainly about _________.

A.the cause of the effects of alcohol

B.unpleasant effects caused by alcohol

C.the advantages of drinking alcohol

D.Asians and alcohol小题3:We can infer from the passage that _________.

A.the ALDH2 deficiency may be passed on from generation to generation

B.about 36 percent of Japanese, Chinese and Koreans are heavy drinkers

C.unpleasant effects occur only when people with this deficiency drink a lot

D.only some East Asians have the ALDH2 deficiency小题4:Esophageal cancer is one of the deadliest cancers because _________.

A.it can’t be treated at all

B.it is hard to be discovered early

C.people are usually addicted to alcohol

D.it is hard to cure once it has developed

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