Some people are walking the bridge and some boats are going the bridge. A. across, acro

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A. across, across
(答案→)B. over, through
C. through, through
D. through, over
解析：此题重点考查介词：across“穿过…的表面”，through“穿过…的内部”，over是在…上方“，句意：一些人正走过桥，一些船正穿过桥。人是在桥的上面走，穿是穿过桥的内部，选B。