knowledge的动词形式为know，其第三人称单数为knows；现在分词为knowing；过去式为knew；过去分词为known；其意思是知道、知悉、了解、认识到、懂得、意识到、确信、确知、肯定等，例如know of sth知道某事、be not to know无从知道；另一动词形式为acknowledge，意思是承认、告知收悉等。
例句：1、I don't know what to make of the new manager.
这位新经理，我不知道怎么评价他才好。
2、These problems are all in your mind,you know.
你知道，这些问题都只是你的凭空想象而已。
3、Some people don't know when they're well off.
有些人身在福中不知福。
4、I did not acknowledge that he had done anything wrong.
我没有承认他犯了什么错。
5、She refuses to acknowledge the need for reform.
她拒不承认改革的必要性。
