Will (1)

 

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

• Oh, I left the door open. I'll go and shut it.
• "What would you like to drink?" "I'll have some coffee, please."
• "Did you call Ann?" "Oh no, I forgot. I'll do it now."
• I'm too tired to walk home. I think I'll take a taxi.

You cannot use the simple present (I do) in these sentences.

• I'll go and shut it. (not I go and shut it)

Do not use will to say what someone has already decided to do or arranged to do.

• I can't meet you tomorrow because my parents are coming to see me. (not my parents will come)

The negative of will is won't (or will not).

• Receptionist: I'm afraid Mr. Wood can't see you until 4:00.
• You:             Oh, in that case I won't wait.

We often use I think I'll...or I don't think I'll...when we decided to do something.

• I think I'll stay home this evening.
• I don't think I'll go out tonight. I'm too tired.

We often use will in these situations.

Offering to do something.

• That bag looks heavy. I'll help you with it. (not I help)
• "I need some money." "Don't worry. I'll lend you some."

Agreeing or refusing to do something.

• A: You know that book I lent you? Can I have it back?
• B: Of course. I'll bring it back this afternoon. (not I bring)
• I've asked John to help me, but he won't.
• The car won't start. (=the car "refuses" to start)

Promising to do something.

• Thank you for lending me the money. I'll pay you back on Friday. (not I pay)
• I won't tell Tom what you said. I promise.
• I promise I'll call you as soon as I arrive.

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

• Will you shut the door, please?
• Will you please be quiet? I'm trying to concentrate.