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幼苗
共回答了26个问题采纳率:76.9% 举报
1.have been done 曾经被 e.g.Taiwan has been taken charge of by the Japanese.
2.have been doing曾经干过一段时间...e.g.I have been walking along the lake.
3.4.是现在分词形式,一般用作状语,如 Having been bitten by a dog,now I am not a dog fan.
Having written the same composition before,I passed the exam with ease.
1年前
2