—— Was the driving pleasant when you went to Mexico last summer?

—— No, it ＿＿＿＿ for four days when we arrived, so the roads were very muddy.

A．was raining

B．had been raining

C．would be raining

D．rained

中美关系开始走上正常化时期的美国总统是  [ ]

A、约翰逊　

B、尼克松　

C、里根　　

D、克林顿