题目内容
20、I doubt whether he can ______ his efforts much longer as he looks so tired.
A. keep on B. keep up C. keep back D. keep from
试题答案
20、B
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题目内容
20、I doubt whether he can ______ his efforts much longer as he looks so tired.
A. keep on B. keep up C. keep back D. keep from
试题答案
20、B