问题补充:
I tried to persuade him to give up the foolish idea, but in , and now he begins to regret.
A. vain
B. turn
C. return
D. case
答案:
(答案→)A. vain
B. turn
C. return
D. case
解析:in vain意为“徒劳地”;in turn意为“依次,轮流”;in return意为“作为回报”;in case意为“万一,以防”。根据句意“我原来极力劝他放弃那个愚蠢的想法,他不听,现在他却开始后悔了”可知,答案为A。