活塞式空压机的日常维护检查方法是（）。 A.一看二听三摸四敲 B.一看二听三敲四摸

（）偏重于降低滤饼水分，适应于较粗物料的脱水。

A.高分子絮凝剂类助滤剂

B.表面活性物质类助滤剂

C.无机盐类助滤剂

D.高分子絮凝剂

在植物叶片中，靠近上表皮的部位气孔比较多， 这样有利于气体的进出。 （　 　）

“鹰击长空，鱼翔浅底，万类霜天竞自由”，这句诗中描述的生物生存的环境是

A．浅底、霜天

B．长空、浅底

C．长空、浅底、霜天

D．长空、霜天

主动控场是指演讲者窥视到现场出现异常情况，当机立断，控制住现场气氛和秩序，使演讲活动得以顺利开展。

Considering the age and his family’s poor living conditions and environments, he was not punished by the police as he should have been.

A. the police did not punish him as he should be
B. the police hadn’t punished him as he should have been
C. the police didn’t punish him as they should have done
D. the police hadn’t punished him like they should have done