题目

When Madam Cuirie did the science experiement again, she was more careful where she _____ a mistake.        A. made   B. has made   C. was making   D. had made 答案：D 解析: 由句意知“犯错误”是发生在“was more careful”之前，故用过去完成时。 【标签】动词时态

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