问题 选择题

横断山区“一山有四季,十里不同天”特点形成的最主要原因是

A.纬度

B.经度

C.海陆

D.地形

答案

答案:D

题目分析:

因为横断山区位于亚热带地区,而且海拔高,从山麓到山顶气候的垂直变化显著,形成从亚热带、温带、亚寒带到高山寒带的气候带,成为“一山有四季,十里不同天”的气候环境,故本题选D。

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(19)空应选择()

A.later

B.then

C.now

D.so

单项选择题 A1/A2型题