( )具有无限法偿能力。A．存款货币 B．本位货币 C．基础货币 D．电子货币

某县居民区有70%的居民饮用河水，此县有一传染病院，其污水未经处理直接排放河流，1976年1～9月伤寒发患者数达200例。而这些患者都集中在河流的下游地带，而饮用河水的人伤寒发病率10.3%，饮用井水的居民伤寒发病率0.54%，此伤寒患者突然增多最可能的原因

A．工业用水管线泄漏

B．供水设备和净化消毒措施未能正常运转

C．医院污水污染水源

D．农业废水污染了水源

E．以上都不是

阅读简答，阅读下列文章，回答问题。

Health experts have warned for many years that cigarette-smoking can lead to heart disease, cancer and other medical problems. And officials say disease caused directly by smoking kill at least three hundred and twenty thousand Americans each year. But smokers still find it rather difficult to stop .The tobacco industry says 40 million Americans continue to smoke cigarette . The American Cancer Society wants to change this. Every year the group organizes a national Non-smoking Day in order to get people to give up cigarette.

On the Non-smoking Day the organization is asking all smokers to stop smoking at least for 24 hours .The Cancer Society hopes this will lead many people to give up smoking completely .On that day the Cancer society officers will give telephone call advice on how to stop smoking. Some others also can call a special telephone to hear recorder messages by doctors. Some factories will offer their workers candy or chewing gum to help them to keep from smoking. Some companies are offering special presents and low prizes to people who sign an agreement to stop smoking. And Americans who don’t smoke are being asked to help just one person who is smoking during the 24-hour campaign.

小题1:How many Americans die from smoking each year ? ﹙不超过4个单词﹚

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小题2:Who set the Non-smoking Day ? ﹙不超过4个单词﹚

                                  .

小题3:What is the purpose of the Non-smoking Day ?﹙不超过7个单词﹚

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一个静止的放射性元素的原子核衰变后，在有匀强磁场的云室中出现两个内切圆轨迹，其轨迹半径之比为45:1，求：

(1)该衰变是属于什么衰变？

(2)衰变前该元素的原子序数多大？

不仅是企业盈利能力指标的核心，同时也是杜邦体系的核心指标是( )。

A．销售利润率

B．总资产报酬率

C．净资产收益率

D．资本保值增值率

短时记忆可以持续两分钟。