That is the only way we can imagine _______ the overuse of water in students’ bathrooms.

A．reducing

B．to reduce

C．reduced

D．reduce

设某企业生产某种产品300吨，其中合格产品270吨，不合格品30吨，则是非标志的标准差为（）

A.90

B.0.3

C.0.09

D.0.9