be可以+名词、形容词，介词短语、非谓语动词（动名词、不定式、分词）。
例句
The marshes have been drained.
沼泽地里的水已排干。
Your trip must have been fun!
你这次旅行一定很开心吧！
Things have been going badly.
事情进展得不顺利。
How could I have been so stupid?
我怎么会这么傻？
You could have been killed!
你本可能被杀了。
There have been some ugly scenes.
出现了一些丑恶的场面。
