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问题 选择题

将等质量的Mg、Al、Fe分别放入三份浓度（即溶质质量分数）相等的稀盐酸中，反应生成的氢气质量与反应时间的关系如图所示．根据图中所给信息，作出的判断错误的是（　　）

A．图线x表示镁的反应情况

B．铝消耗的稀盐酸质量最大

C．镁一定过量，铝、铁可能反应完

D．镁和铁一定过量，铝可能反应完

答案

A、镁最活泼，与稀盐酸反应时需要的时间最短，图线x表示镁的反应情况．正确．

B、铝不如镁活泼，比铁活泼，反应需要的时间介于镁和铁之间，图线y表示铝的反应情况，Mg、Al、Fe与稀盐酸反应的化学方程式分别为：

Mg+2HCl═MgCl2+H2↑、2Al+6HCl═AlCl3+3H2↑、Fe+2HCl═FeCl2+H2↑，由化学方程式可知，当生成的氢气质量相等时，消耗的稀盐酸质量相等，铝与稀盐酸反应生成的氢气最多，消耗的稀盐酸质量最大．正确．

C、如果镁不过量，等质量的镁、铁与稀盐酸反应生成的氢气不可能相等，所以镁一定过量，铝、铁可能反应完．正确．

D、如果镁和铁都过量，那么铝一定过量，Mg、Al、Fe都过量时，生成的氢气质量应该相等，与图中信息不符．错误．

故选：D．

完形填空

根据下面短文内容，在短文的空格处填上一个恰当的词，使短文完整、通顺。

People usually check whether their keys, wallets and phones are with them___小题1:___ going out. But many people in Chain now have one more important thing to take, a face mask(面罩). They hope that it __小题2:____ protect them from polluted air.

Since January, many cities in China have seen a lot of hazy(雾蒙蒙的)days. In Beijing, ____小题3:___five days in January were free of smog(雾霾). People in Xi’an only saw a blue sky on one day in February. Smog is dirty air that ___小题4:___like fog and smoke.

An official for the Ministry of Environmental Protection told Beijing News that PM2.5 pollution is the main problem with air pollution. PM2.5 refers to pollution with small particles(颗粒) of 2.5 micrometers(微米) or less in diameter(直径).

According to the Chinese Academy of Sciences, ___小题5:_____cars and burning coal(煤) are two major factors(原因) for PM2,5.

Poor air is___小题6:___ for people’s health, especially for children and the elderly. A report from Beijing Children’s Hospital shows that from Jan 5 to 11, half of the patients in the internal medicine department(内科门诊) are there for respiratory(呼吸) problems.

Air problems and environmental protection have become a concern(关切的事) for the whole nation. Premier Wen Jiabao___小题7:____ his last Government Work Report on March 5. the report said that the government should work hard to prevent pollution and give people a ____小题8:____living environment.

It calls on people to make full use of energy and resources and cut down on energy use.
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单项选择题

在其他条件一定的情况下，关于劳动力需求的说法，正确的是（）。

A.在工资率上升时，劳动力需求量会下降

B.在劳动力供给增加时，劳动力需求数量下降

C.在产品需求增加时，劳动力需求数量会下降

D.资本的价格对于劳动力需求数量不会产生影响
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