题目内容：

The poorer mental function seen among alcoholics，many of whom also regularly smoke cigarettes，may be partly due to the long term effects of nicotine(尼古丁)，new research suggests.

“People who are also smokers are at a much higher risk，” Dr.Jennifer  M.Glass of the University of Michigan's Addiction Research Center said. In her study，“Cigarette smoking has a bad effect on IQ and thinking，” she said.

This finding may seem counterintuitive(违反直觉的)，since many smokers show that they feel quicker and focused after smoking. Indeed，research shows that improved mental functioning is one of the immediate effects of nicotine exposure. Chronic(慢性的)smoking，however，is known to have the opposite effect. Studies show that up to 87 percent of alcoholics smoke cigarettes.

Yet，few studies have looked into cigarette smoking as a factor that might explain the cognitive(认知的)lack reported among alcoholics. To search for that association，Glass and her colleagues examined brain function among 172 men from the same area，including 103 men who abused alcohol. The team found that men with higher scores on the lifetime alcohol problems scale(LAPS)and those who reported a higher number of pack years of smoking both had lower IQ scores.

Upon further research，the researchers found that smoking also appeared to be independently associated  with weaker word and space reasoning.

Thus，though smoking did not account for all of the decreased mental functioning observed among the alcohol abusers，it did seem to account for some of the effects，the report indicates.

1.What is the passage mainly about?

A．Cigarette smoking contributes to decreased IQ and thinking.

B．Alcohol abuse is to blame for the poorer mental function.

C．Most of the alcoholics are also heavy smokers.

D．Non-smokers mostly have higher IQ scores.

2.The underline sentence “Chronic smoking, however, is known to have opposite effect” in paragraph 3  suggests:

A．Chronic smoking can improve mental functioning.

B．Chronic smoking has an immediate influence on mental functioning.

C．Chronic smoking has side effect on mental functioning improvement.

D．Chronic smokers feel quicker and focused after smoking.

3.From the passage we can learn that .

A．cigarette smoking is not related to reasoning

B．nicotine exposure can improve mental functioning temporarily

C．the long term effects of nicotine cause alcoholics

D．men with lower scores on the LAPS have lower IQ scores

4.It can be inferred from the passage that .

A．many alcoholics suffer a great deal from smoking

B．giving up smoking is significantly challenging for the alcoholics

C．alcoholics who do not smoke much have higher IQ scores

D．other factors can cause the poorer mental functioning besides smoking

5.The purpose of this passage is .

A．to warn us of the bad effects of smoking on IQ and thinking

B．to tell us why people are addicted to smoking

C．to give us some advice on how to improve IQ and reasoning

D．to compare the bad effects of alcohol and cigarette