题目内容：

I couldn't get there on time because of the heavy snow yesterday.(同义句改写)
I couldn't get there on time ____ it ____ heavily yesterday.

优质解答

because snowed
因为是从结构看it ____ heavily yesterday,这应该是原因状语从句,故用从属连词because
再由于从句中时间状语是yesterday 这个过去时间状语,故用一般过去时