On many trains and buses, there are some special seats out for senior citizens. A. markin

发布时间：2020-08-17 02:04:02

On many trains and buses, there are some special seats      out for senior citizens.
A. marking
B. marked
C. to mark
D. mark

网友回答

A. marking
(答案→)B. marked
C. to mark
D. mark
解析：句意：在许多火车和汽车上，有一些专门的座位被事先划定给老人。seats 与mark之间为被动关系，故使用过去分词。
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