-I have mended that cup for you.

-Thanks, but you needn't have ________. I bought a new one this morning.[ ]

A．helped  

B．required

C．wasted  

D．bothered

以下哪项不属于轻声的作用（）

A、修辞作用

B、区别词义

C、区别词性

D、使语流顺畅