( )是以后验证设备设计是否达到规定要求以及评审设计和规范质量优劣程度的依据。

A．设计输出

B．设计输入

C．设计评审

D．设计确认

— Why does the boy keep crying?

— It is ______ he has lost his favorite car model.

A．since

B．so

C．when

D．because