We offered our congratulations ________ his passing the college entrance exams．

We offered our congratulations ________ his passing the college entrance exams．

A.at

B.on

C.for

D.of

答案及解析： B

解析：

congratulate指对人祝贺，如表达“就某事祝贺”，一般用介词on。congratulate sb．on sth．意为“为某事而祝贺某人”。