Will ( Future simple )

   A. We use I'll (= I will) when we decide to do something at the time of speaking:

  * Oh, I've left the door open. I'll go and shut it.

  * 'What would you like to drink?' 'I'll have an orange juice, please.'

  * 'Did you phone Ruth?' 'Oh no, I forgot. I'll phone her now.'

  You cannot use the present simple (I do/I go etc.) in these sentences:

  * I'll go and shut the door. (not 'I go and shut')

  We often use I think I'll ... and I don't think I'll ...:

  * I feel a bit hungry. I think I'll have something to cat.

  * I don't think I'll go out tonight. I'm too tired.

  In spoken English the negative of will is usually won't (= will not):

  * I can see you're busy, so I won't stay long.

    B. Do not use will to talk about what you have already decided or arranged to do (see Units 19-20):

  * I'm going on holiday next Saturday. (not 'I'll go')

  * Are you working tomorrow? (not 'will you work')

    C. We often use will in these situations:

  Offering to do something

  * That bag looks heavy. I'll help you with it. (not 'I help')

  Agreeing to do something

  * A: You know that book I lent you. Can I have it back if you've finished with it?

     B: Of course. I'll give it to you this afternoon. (not 'I give')

  Promising to do something

  * Thanks for lending me the money. I'll pay you back on Friday. (not 'I pay')

  * I won't tell anyone what happened. I promise.

  Asking somebody to do something (Will you ...?)

  * Will you please be quiet? I'm trying to concentrate.

  * Will you shut the door, please?

  You can use won't to say that somebody refuses to do something:

  * I've tried to advise her but she won't listen. (= she refuses to listen)

  * The car won't start. I wonder what's wrong with it. (= the car 'refuses' to start)