Know | Know How To

Know cannot be followed directly by an infinitive. We use the structure know how to.

  • I know how to make French fries.

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

  • I knew him to be an honest man.

However, this is unusual; that-clauses are generally more natural.

  • I knew that he was an honest man.


Know cannot normally be used in the progressive form.

  • I know what you mean. (NOT I am knowing —)

Know and know about/of

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


  • ‘Do you know my brother?’ ‘No, I have never met him.’
  • We all know about Albert Einstein. (NOT We all know Albert Einstein.)

I know and I know it

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

  • ‘You are late.’ ‘I know. ’ (= I know that I am late.)

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

  • ‘We went to a nice restaurant called Fire and Ice last night.’ ‘I know it. ’ (= I have heard of that restaurant.)
  • ‘We went to a nice restaurant called Fire and Ice last night.’ ‘I know.’ (=I know that you went to that restaurant.)

Manjusha Nambiar

Hi, I am Manjusha. This is my blog where I give English grammar lessons and worksheets.

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