硅胶吸附性能很好，它对极性物质的选择性十分强.

采煤方法的选择必须符合安全、经济、煤炭回收率高的基本原则。

在急救现场如有少量肠管脱出，采取（）

A.送回腹腔

B.消毒单包裹

C.用清洁碗覆盖保护包扎

D.消毒后送回腹腔

E.用消毒碗覆盖保护包扎

The teenage year from 13 to 19 were the most difficult time for me . They were also the best and worse years in my life . At the first, I thought I knew everything and could make decisions by yourself. However, my parents didn’t seem to think such. They always tell me what to do and how to do it. At one time , I even felt my parents couldn’t understand me so I hoped I could be freely from them. I showed them I was independent by wear strange clothes. Now I am leaving home to college. At last, I will be on my own, but I still want to have my parents to turn to whenever need help.

3（）

下列各项中，（）不属于计量法的调整范围和调整对象。

A、建立计量基准、标准

B、进行计量检定

C、教学示范中使用的或家庭自用的计量器具

D、制造、修理、销售、使用的计量器具等

电磁四通换向阀的滑块在阀中左右移动，是因为存在（）的原因。

A、电位差

B、温度差

C、压力差

D、位能差