作业帮求救!波若波罗密!英语大神降临吧!By the time he was twelve, Edison had begun to make a living by himself. 到了十二岁那年,爱迪生开始自己谋生.‖为什么用过去完成时?
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求救!波若波罗密!英语大神降临吧!By the time he was twelve, Edison had begun to make a living by himself. 到了十二岁那年,爱迪生开始自己谋生.‖为什么用过去完成时?
求救!波若波罗密!英语大神降临吧!
By the time he was twelve, Edison had begun to make a living by himself. 到了十二岁那年,爱迪生开始自己谋生.‖为什么用过去完成时?
求救!波若波罗密!英语大神降临吧!By the time he was twelve, Edison had begun to make a living by himself. 到了十二岁那年,爱迪生开始自己谋生.‖为什么用过去完成时?
by the time:意为:在.之前已经.
by+时间名词意为：“到…时（已发生某事),一般用于完成时态,这是固定用法,理解时朝这个方向就是了.
给你几个例句:
By the time police got there,armstrong had already taken the fatal plunge with her children.
等到警察到了那里,阿姆斯特朗已经采取了与她的孩子致命的大幅下挫.
By the time our teacher came in ,we had started speaking English.
在老师进来前,我们都已经开始讲英语了
By the time the rescuing ship arrived,titanic had sunk without trace.
待到营救的船只赶到的时候,泰坦尼克考已经消失的无影无踪了.
具体问题具体分析,如有错误请指出,