be done用于被動語態(tài)
之所以是being 是因為前面有個介詞（介詞后動詞用ing形式）
希望你能理解 不懂還可以繼續(xù)問.那么這句"It is being repaired by a friend of my father's"中“is”也不是介詞啊，為什么也用“being”呢？系動詞am is are后面要用ing形式。這個…你應(yīng)該是懂得吧…a friend of my father repair it .It is repaired by a friend of my father.為了表示進行時態(tài)所以it is being repaired by a friend of my father.希望你能理解。被動語態(tài)的題做多了就不難了。剛開始還是會有一點混。加油