题目内容：

Don't use words,expressions,or phrases____only to people with specific knowledge.
A being known
B having been known
C to be known
D known
为什么 还有D是现在完成时的被动语态吗?
有人说：其实这个句子写成定语从句，是这样：Dont't use words,expressions,or phrases that are known only to people with specific knowledge.
我们可以把that are 省略。
为什么that are 可以省略呢

优质解答

that are省略是一种说法,不用较真,意思是说定语从句可以用非谓语动词来替代,因为更简单.至于为什么是d,是因为d最贴切a,b,c在某些情况下也是对的,a.being known,是被动的现在进行形式.比如the boy being beaten那个正...