KR—20常用来反映研究工具信度的________。

如图，电解用粗盐(含、、等杂质)配制的食盐水，以下说法正确的是

A．a是电解池的正极

B．a电极上发生还原反应

C．b电极附近有白色沉淀出现

D．b电极上有黄绿色气体产生

关于我国气候特征的叙述，正确的是[ ]

A、气候复杂多样

B、气候类型单一

C、季风气候显著

D、大陆性气候显著

读“黄土高原生态环境恶性循环示意图”，完成下列要求

（1）选择下列项目前的字母填入图中空格中（每项只使用一次），完成整个循环过程．

A、农作物产量下降               B、人均耕地少，燃料需求增加

C、扩大荒地开垦面积             D、破坏植被，开垦荒地，砍伐森林

（2）治理黄土高原地区水土流失的措施中，你认为最重要的是______．

Why do I want to go to college No one has ever asked me  （1）  a question. But many times I have asked myself. I have（2）a whole variety of reasons.  （3） important reason is that I want to be a better man.Many things make human beings different  （4）or better than or even superior to animals.One of the most important things is（5）. If I fail to receive higher education, my education.（6） As I want to be a fully  （7）man, I must get a well-rounded education, which good colleges and universities are supposed to （8）. I know one can get educated in many ways, but colleges and universities are（9）the best places to teach me how to educate myself. Only when I am well-educated, will I be a better human being and（10） fit into society.

第（4）空应选择（）

A. to       

B. around    

C. between      

D. from