He was busy writing the exam paper , only ___once in a while to check the time. A. to stop B. stopp...
2022-12-29 12:16:24 31次 2014届广东省汕头市高二10月月考英语试卷（解析版） 单项填空 反馈错误 加入收藏 正确率 : 100%
题目内容：
He was busy writing the exam paper ,
only ___once in a while to check the time.
A. to stop B.
stopping C.
to have stopped D. having stopped
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