— People should spare no effort to protect the environment.

— ________.Air pollution, as is known to all, does harm to our health.[      ]

A. All right  

B. Fine

C. Go ahead  

D. Exactly

货物招标在保证货物质量的前提下，货物必须遵守( )原则。

A．低成本

B．低价格

C．低消耗

D．低费用

E．高质量