I just don’t understand _______ that prevents so many Americans from being as happy as one might exp...
2022-11-01 17:10:14 25次 2014-2015学年天津河西区高三下学期总复习质量调查三英语试卷（解析版） 单项填空 反馈错误 加入收藏 正确率 : 100%
题目内容：
I just don’t understand _______ that prevents so many Americans from being as happy as one might expect.
A. why it does B. what it does
C. what it is D. why it is
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