楼主说的可是过去分词做状语表示被动的情况?如果是这种情况,则可以不用be动词,
e.g.He may not come to the party tonight,forbidden to go out by his parents.
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如果是两个动词同时充当谓语表示并列,而后一个动词又有被动的意思,那麼要视前一个动词是否使用be动词而定,
1.前一个动词使用be动词,但是不是表示被动,则后一个动词必须要加be动词
e.g.She was insisting writing out the truth while was told to stop by some politicians.
但是这句话最好讲成：While told to stop by some politicians,she was insisting writing out the truth.把后一个动词变成状语放在句首.
2.前一个动词使用be动词,同时示被动,则后一个动词可省略be动词
e.g.This photo was found in the dustbin and then sent to the FBI.
3.前一个动词不使用be动词,后一个动词如果表示被动则需要加上be动词
e.g.This guy stole the precious vase and was caught by the cops a month later.
