Though _____ many times, the song still sounds as nice as before   [ ]

A. it was heard  

B. hearing

C. heard

D. to be heard

主承销商应当在证券上市后向中国证监会报备承销总结报告，报告应提供( )文件。

A．募集说明书单行本

B．承销协议及承销团协议

C．律师鉴证意见

D．会计师事务所验资报告