搜题请搜索小程序“爱下问搜题”
问题 多项选择题

下列关于施工场地照明器具选择的说法正确的是( )。

A．含有大量尘埃但无爆炸和火灾危险的场所，应采用防尘型照明器

B．对有爆炸和火灾危险的场所，应按危险场所等级选择相应的防爆型照明器

C．在振动较大的场所，应选用防爆型照明器

D．正常湿度时，选用开启式照明器

E．对有酸碱等强腐蚀的场所，应采用耐酸碱型照明器

答案

参考答案：A,B,D,E

单项选择题 B1型题

产后营血亏虚，经脉失养可导致的上述病证是（）

A.产后恶露不绝

B.产后身痛

C.产后发热

D.产后自汗

E.产后缺乳
查看答案
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.

17（）

A.many 

B.a few 

C.a little 

D.fewer
查看答案