—Was the trip pleasant when you vacationed in the mountain village last summer?

—No，it__________for four days when we arrived，so the roads were very muddy.

A．was raining

B．would be raining

C．had been raining

D．have rained

人力资源需求根源于（）。

A、社会消费

B、用人单位

C、经济体制

D、市场类型