know的过去式形式为knew。know作为动词，中文含义有“知道”、“知悉”、“了解”、“认识到”、“懂得”、“意识到”、“确信”、“确知”、“肯定”等，第三人称为knows，现在分词为knowing，过去分词为known。
know的基本释义及用法介绍
know作为动词，意为知道;知悉;了解;认识到;懂得;意识到;确信;确知;肯定。其过去式为knew，过去分词为known，现在分词为knowing。例句有：
1、The cause of the fire is not yet known.
火灾的原因尚不清楚。
2、It is widely known that CFCs can damage the ozone layer.
众所周知氯氟烃会破坏臭氧层。
3、I didn't know what he was talking about.
我不知道他在谈什么。
4、I know of at least two people who did the same thing.
我知道至少有两人干过同样的事。
5、I knew perfectly well what she meant.
我完全懂她的意思。
6、He knew (that) he could trust her.
他确信她是可以信赖的。
7、I've known David for 20 years.
我认识戴维已有20年了。
8、She is best known for her work on the human brain.
她在对人脑的研究方面最为知名。
9、The drug is commonly known as Ecstasy.
这种药通常称作摇头丸。
10、She knows a bargain when she sees one.
她一看就知道有没有便宜可捡。
