-Sorry I have to now. It’s time for class.-OK I’ll call back later.A. hang upB.

问题补充：

---- Sorry, I have to now. It’s time for class.

---- OK, I’ll call back later.

A. hang up

B. break up

C. give up

D. hold up

答案：

(答案→)A. hang up

B. break up

C. give up

D. hold up

解析：词义辨析题。A. hang up 挂断电话 B. break up 解散 C. give up放弃 D. hold up 坚持住“很抱歉我要挂电话了，上课时间到了”“好的，一会我再打电话给你”根据回答当中的call back可知双方是在通电话，所以选择与打电话有关的词语。