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问题 填空题

如图是甲、乙、丙三种物质（均不含结晶水）的溶解度曲线．现有t2℃时甲、乙、丙三种物质的饱和溶液（无固体存在），请根据右图回答：

（1）t2℃时，将三种饱和溶液分别恒温蒸发相同质量的水，析出晶体最多的是______；

（2）将三种饱和溶液分别从t2℃降温到t1℃时，所得溶液中溶质的质量分数由大到小的顺序为______．

答案

（1）t2℃时，甲乙丙三种物质的溶解度由大到小得顺序为甲＞乙＞丙，蒸发相同质量的水，析出晶体最多的是甲，所以本题答案为：甲；

（2）将三种饱和溶液分别从t2℃降温到t1℃时，随着温度的改变，溶解度降低的应该看新温度下的溶解度，因为其有晶体析出；而丙则是随温度降低而溶解度增大的，所以应该看原温度下的溶解度，这三个数值，是乙的最大，其次是甲，再次是丙．所以本题答案为：乙＞甲＞丙．

单项选择题 B型题

每克焦痂下组织细菌数量超过105个并向邻近未烧伤组织侵袭，产生全身感染症状（）。

A.烧伤创面脓毒症

B.脓毒血症

C.烧伤败血症

D.全身炎症反应综合征

E.蜂窝织炎
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单项选择题

It is clear that some chemicals can damage the health of animals and humans. (1) , this is not the only problem that (2) be caused by the careless use of chemicals. Chemicals can also (3) the ecological balance of the environment. If the ecological balance is disturbed, the results can be (4) serious.

The (5) of DDT illustrates the problem. DDT, a chemical which kills insects, at first seemed to be a perfect answer (6) many problems. It would control insects that caused dangerous diseases, (7) insects that caused billions of dollars of damage to crops every year. Governments permitted and even (8) the use of DDT. Farmers in many countries (9) to spray it on their crops. The (10) results were good: Damage to crops (11) down, and profits went up. However, the chemical had effects which the scientists didn’t see in (12) . First, it also killed insects which were the (13) enemies of the harmful insects and which were therefore beneficial to farmers. Second, and perhaps worse, DDT did not kill (14) harmful insect. A few insects had natural resistance to the chemical. They (15) and reproduced in large numbers. In a few years there were large numbers of insects which were not (16) by DDT, and there were (17) insects which could act as natural (18) on these new "super-insects". Finally, it became clear that DDT was not solving the insect problem. In fact, it was making the problem worse. It (19) became necessary to find a second (20) for the effects of the first.

8（）

A.asked 

B.requested 

C.declared 

D.encouraged
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