— I'm sure Andrew will come out first in this gymnastic competition.

— I think so. He ________ for it for months.[ ]

 A. is preparing  

B. was preparing

C. had been preparing  

D. has been preparing

我国解决水资源季节变化大的最好办法是（　　）

A．节约用水

B．跨流域调水

C．兴修水库

D．防止水污染