I want to ring him＿＿＿to know the reason why he rang＿＿＿while I was speaking yesterday.

I want to ring him＿＿＿to know the reason why he rang＿＿＿while I was speaking yesterday.

A.up； off

B.back； up

C.up； down

D.on； off

答案及解析： A

ring sb. up意为“给某人打电话”；ring off的意思是“挂断电话”。