问题描述：
英语句型转换（急!）(只有一句）
The scientist made the great invention when he was over seyenty.(保持原句意思）
The scientist made the great invention ________ his _______.
The scientist made the great invention when he was over seyenty.(保持原句意思）
The scientist made the great invention ________ his _______.
问题解答：
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