Listening to loud music at rock concerts caused hearing loss in some teenagers.A. isB. ar

问题补充：

Listening to loud music at rock concerts caused hearing loss in some teenagers.

A. is

B. are

C. has

D. have

答案：

A. is

B. are

(答案→)C. has

D. have

解析：考查时态，动作就已经发生，对现在造成的影响，所以用现在完成式，因为主语是单数，所以用has，句子意思“听大声的摇滚音乐已经造成一些青少年丧失听力”，所以选C