being done / be being done / have been doing / having been done 有没有谁可以帮我好好分析一下

being done；现在分词的被动语态,修饰名词,置于名词后面,作定语,相当于现在进行时的定语从句.例如；the house（ being built）=the house （which/that is being built）be being done; 现在进行时的被动语态,作谓语...being done 是不是都只是用来修饰名词，有时当它放在句首时又如何理解？ being done 和 be being done 是不是都是理解成某物现在正被怎样怎样？谢谢。being done放在名词后修饰名词没错。它放在句首时 作状语，相当于状语从句。being done 和 be being done 都可理解成某物现在正被.....但后者作谓语，前者做状语，置于句首。