How long have they this new car?A. boughtB. buyC. haveD. had

问题补充：

How long have they this new car?

A. bought

B. buy

C. have

D. had

答案：

A. bought

B. buy

C. have

(答案→)D. had

解析：根据疑问词how long多久可知文中不能用瞬间动词,have为完成时态助动词,后面动词要用过去分词,故选D.