Brown said he was by no means annoyed; ______, he was glad to be able to make himself clearly understood.

A．all in all

B．for one thing

C．on the contrary

D．by the way

工程项目承包单位投标时，按规定应提交下列证明文件( )。

A．只交验企业法人营业执照

B．只交验企业等级证书

C．优良工程证书

D．企业法人营业执照和企业等级证书