分别被植物学家和动物学家看成是植物和动物的是（）。
A.鞭毛变形虫
B.海绵
C.眼虫
D.海葵
参考答案：C
He is no longer in good condition, and his ability to work is limited. I ____________ him to give up the job but failed.
A．suggested
B．persuaded
C．tried to persuade
D．managed
放大器输出与输入保持一段距离其目的是（）。
A、便于安装
B、便于散热
C、减少输出级与输入级之间寄生耦合
D、便于检修
