Skip to main content

know

know how + infinitive​

Know is not followed directly by infinitives. We use know how to (see here).

  • I know how to make Spanish omelettes. (not I know to make …)

Object + infinitive​

In a formal style, know is sometimes followed by object + infinitive.

  • They knew him to be a dangerous criminal.

The passive equivalent is quite common in a formal style.

  • He was known to be a dangerous criminal.

In a less formal style, that-clauses are more usual.

  • They knew that he was a dangerous criminal.

Know means ‘experience’ in the common structure I’ve never known + object + infinitive; an infinitive without to is possible in British English.

  • I’ve never known it (to) rain like this.

Tenses​

Know cannot usually be used in progressive forms (see here).

  • I know exactly what you mean. (not I am knowing …)

A present perfect tense is used to say how long one has known somebody or something. (see here) for more details.)

  • We’ve known each other since 1994. (not We know each other since 1994.)

know and know about/of​

Know + object is used mainly to talk about knowledge that comes from direct personal experience. In other cases, we normally use know about/of, have heard of or another structure. Compare:

  • ‘You don’t know my mother, do you?’ ‘No, I’ve never met her.’
  • We all know about Abraham Lincoln. (not We all know Abraham Lincoln.)

know and find out, etc​

Know is not normally used to talk about finding something out: to know something is to have learnt it, not to learn it. To talk about getting knowledge we can use for example find out, get to know, learn, hear, can tell.

  • ‘She’s married.’ ‘Where did you find that out?’ (not … Where did you know that?)
  • I want to travel round the world and get to know people from different countries. (not … and know people …)
  • He’s from Liverpool, as you can tell from his accent. (not … as you can know from his accent.)

I know and I know it​

Note the difference between these two short answers.

I know refers to facts – it could be completed by a that-clause.

  • ‘You’re late.’ ‘I know.’ (= I know that I’m late.)

I know it generally refers to things – it replaces a noun.

  • ‘I went to a nice restaurant called The Elizabeth last night.’ ‘I know it.’ (= I know the restaurant.)
note

For ways of using you know, (see here).