If the weather had been better, we could have had a picnic. But it ____ all day.

A．rained

B．rains

C．has rained

D．is raining

国家计划中主要依靠经济手段来保证其实施的计划是

A．长期计划

B．中期计划

C．指令性计划

D．指导性计划