_______ let fake products become uncontrolled in the market.

A．In certain circumstances we can

B．In no circumstance can we

C．Under any circumstances we can

D．Under no circumstances can we

在家庭生产理论中，家务劳动是一种( )。

A．生产性劳动
B．服务性劳动
C．义务劳动
D．消闲活动