17..In the United States bus travel doesn't cost much as train travel 　　?18.A. don't the

问题补充：

17..In the United States, bus travel doesn cost much as train travel, ?

18.

A. don they

B. does it

C. do they

D. doesn it

答案：

A. don they

(答案→)B. does it

C. do they

D. doesn it

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