his financial problems , his wife also left him , which made him very depressed .

A．In case of

B．Except

C．On top of

D．On account of

为了使用户能听清话务员的讲话，要求话务员一定要吐字清晰、（）。

A、态度和蔼

B、语气平淡

C、操作熟练

D、语速适中