knowing是什么意思

　　I stood there blankly, not knowing what to do.

　　我茫然地站在那里，不知道该怎么办。

　　Knowing the bad news, all of us sat in silence.

　　知道这个坏消息之后，我们一声不吭地坐着。

　　There was no way of knowing, save by going down.

　　除了下去，没有别的办法知道。