30. After he had recovered from his injury, he caught a squirrel (松鼠) and raised it as a pet. Soon he ______ home snakes and other creatures from the woods near his school.

A．was bringing

B．is bringing

C．has brought

D．had brought

发电机按（）的不同可分为水轮发电机、汽轮发电机、风力发电机、太阳能发电机、柴油发电机和汽油发电机等。

A.噪音的大小

B.能否移动

C.应用能源的类型

D.产生电的特性