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问题 单项选择题

麻醉维持期的通气方式（）

A.只能是控制呼吸

B.可以是自主的、辅助的和控制性呼吸

C.只能是喉罩或气管插管控制呼吸

D.术前应用抗酸药可以长时间面罩通气

E.对于有自主呼吸的肥胖病人可以放置口咽通气管优于放置喉罩

答案

参考答案：B

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.

20（）

A.cause 

B.insect 

C.answer 

D.cure
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单项选择题

患者，女性，54岁，心悸2h来院急诊。查体：心率125/min，脉率105/min，心脏听诊心音强弱及快慢不等。考虑是

A．窦性心动过速
B．频发房性期前收缩
C．阵发性室上性心动过速
D．阵发性快速房颤
E．频发室性期前收缩
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