We would have called a taxi yesterday if Harold us a ride home.
A. didn't offer
B. wouldn't offer
C. hasn't offered
D. hadn't offered
网友回答
A. didn't offer
B. wouldn't offer
C. hasn't offered
(答案→)D. hadn't offered
解析：考查虚拟语气。本题是条件状语从句的虚拟语气，从句中用过去完成时表示与过去事实相反，主句用情态动词+have done.故D正确。