场地设计时所需的降水资料一般有( )。

A．平均年降雨量

B．年最低降雨日期

C．暴雨持续时间及其最大降雨量

D．初终雪日期

— Did you know any Chinese before you arrived in Beijing?

— Never ________ it, actually.

A．had I learned

B．have I learned

C．I have learned

D．I had learned