from和by同时加动名词 用哪个 为什么from既可以跟助动词,也能跟be动词?

by\u540e\u9762\u4ec0\u4e48\u65f6\u5019\u7528\u540d\u8bcd\uff0c\u4ec0\u4e48\u65f6\u5019\u7528\u52a8\u540d\u8bcd\uff1f\u9ebb\u70e6\u8be6\u7ec6\u70b9

\u55ef...\u5c31\u6211\u6240\u77e5\uff0cby\u540e\u9762\u53ef\u4ee5\u63a5\u4ea4\u901a\u5de5\u5177\u554a\uff0c\u4f8b\uff1aby bus .by car\u50cfbus\u3001car\u3001air\u8fd9\u4e9b\u90fd\u662f\u540d\u8bcd\u561b\u3002\u8fd8\u6709\u56fa\u5b9a\u7684\u77ed\u8bed\u4e9b\uff0c\u4f8b\uff1aby oneself\u3001by accident \u3001by chance \u3001 by mistake \u8fd9\u4e9b\u554a\u540e\u9762\u63a5\u7684\u4e5f\u90fd\u662f\u540d\u8bcd\u561b\u3002

from\u672c\u8eab\u662f\u53ef\u4ee5\u8ddfbe\u52a8\u8bcd\u7684\uff0c\u4f46\u8ddf\u52a9\u52a8\u8bcd\u4e00\u5b9a\u662f\u5728\u8ddf\u53e6\u4e00\u4e2a\u5b9e\u610f\u52a8\u8bcd\u4e00\u8d77\u7528\u7684\u65f6\u5019\u3002
He is from London.
He didn't come from London, but from Liverpool.

没有说法啊，看需要哪个介词。
例如： prevent/stop/prevent......from doing
by + doing通过某种方式
很高兴为你解答！
老师祝你学习进步！
望采纳，多谢你的问题！^_^

对by asking the teacher for help提问用什么

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