题目

It was a great _____ for him to be pleasant to people he didn't like. A. attempt    B. trouble   C. power    D. effort 答案：D 解析:    effort （作可数名词用） （=vigorous attempt） 努力的尝试：Does it require a great effort of will to give up smoking? （戒烟需要坚强的毅力吗？）

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