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问题 单项选择题

下列对队列的叙述中正确的是( )。

A．队列属于非线性表

B．队列按“先进后出”原则组织数据

C．队列在队尾删除数据

D．队列按“先进先出”原则组织数据

答案

参考答案：D

解析： 队列是指允许在一端进行插入、而在另一端进行删除的线性表，允许插入的一端称为队尾，允许删除的一端称为队头。它又称为“先进先出”或“后进后出”的线性表，体现了“先来先服务”的原则。

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.

18（）

A.controls 

B.enemies 

C.choices 

D.means
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多项选择题

建设单位组织验收小组进行初步验收时，（）应给予积极配合。

A.施工单位

B.监理单位

C.设计单位

D.设备供应及代理商
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