【题目】After the quarrel, I tried to fix the misunderstanding between us, but all my efforts seemed ______.
A. in need B. in peace C. in vain D. in trouble
在线课程【答案】C
【解析】
试题分析：A. in need需要；B. in peace和平；C. in vain徒劳；D. in trouble麻烦。句意：发生了争吵之后，我努力去解决我们之间的误解，但我所有的努力似乎都很徒劳。结合句意可知选C。