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问题 单项选择题

关于水灰比对混凝土强度的影响，下列叙述不正确的是( )。

A．水灰比越大，与集料粘结力越小

B．水灰比越大，流动性越好

C．水灰比越大，水泥石强度越低

D．水灰比越大，混凝土强度越高

答案

参考答案：D

单项选择题 A3型题

马，沉郁，嗜睡，消瘦虚弱，被毛粗乱，可视黏膜苍白，不耐运动，心率和脉搏增加，食欲减退、全身水肿。血检红细胞数、血红蛋白含量和红细胞压积容量减少。治疗原则中不包括（）

A.止血

B.补充造血物质

C.恢复血容量

D.镇静

E.刺激骨髓造血机能
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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.

第（15）空应选择（）

A．lived

B．died

C．cried

D．survived
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