在污染的水体中最常见的寡毛类是（）。
A.瓢体虫和颤蚓
B.仙女虫和带丝虫
C.颤蚓和水丝蚓
D.仙女虫和瓢体虫
参考答案：C
Mr. Black was old, but able to _______quickly to changes in technology. [ ]
A. reply
B. apply
C. contribute
D. respond
