fall down 和 fall off down 是副词, 后边不接名词代词; off是介词, 后边接名词代词。He feel down from the bike.如有名词代词,还要加from.He fell off the bike .
fall down 和 fall off down 是副词, 后边不接名词代词; off是介词, 后边接名词代词。He feel down from the bike.如有名词代词,还要加from.He fell off the bike .
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