【单选题】________ pears do you have? Three. [ ]
【简答题】阅读理解。 What do you think of a forest, what do you see? Just trees? Or do you see many other things, such as singing birds, colorful plants and wild flowers? The forest is a whole of its own. It is full...
【简答题】阅读理解。 What do you think of a forest, what do you see? Just trees? Or do you see many other things, such as singing birds, colorful plants and wild flowers? The forest is a whole of its own. It is full...
【判断题】四冲程发动机完成一个工作循环进、排气门各开、闭两次。
【单选题】下列关于水体富营养化危害及防治方法描述正确的是______。
A.
导致水体富营养化的主要因素是水体中有机物的增加
B.
河流与浅层缓流的湖泊相比,更容易爆发水体富营养化
C.
在合适的环境条件下,水体中的氨氮可通过微生物的反硝化作用去除
D.
藻类大量繁殖不仅影响水生生态结构,对饮用水处理也有不利影响