____ several times, the young scientist still kept on doing his experiments. A．Having failed B．Havin...
2022-12-22 20:08:50 62次 2014届宁夏高二上学期期末考试英语试卷（解析版） 单项填空 反馈错误 加入收藏 正确率 : 100%
题目内容：
____ several times, the young scientist still kept on
doing his experiments.
A．Having failed B．Having been
failed C．Failed D．To fail
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