EGrammar Unit 20 - Will (1)

We use "I'll" when we decide to do something at the time of speaking.
今回は「will」これは話している時に何かをすることに決めた場合に使います。

決断した時のwill

Oh I left the door open. I'll go and shut it. (not "I go and shut it")
"Did you call Julie?" "Oh no, I forgot. I'll call her now."
I'm a little hungry. I think I"ll have something to eat.
I don't think I'll go out tonight. I'm too tired.
I can see you're busy, so I won't stay long.

Do not use "will" to talk about what you have already decided or arranged to do.
あらかじめ決めていたこと、調整していたことについてはwillは使いません。

I'm leaving on vacation next Saturday. (not "I'll leave")
Are you working tomorrow? (not "Will you work")

willとshall

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
  • "You know that book I lent you? Could I have it back if you're finished with it? " "Of corse. I'll give it to you this afternoon."
• promising to do something
  • "Thanks for lending me the money. I'll pay you back on Friday."
  • "I won't tell anyone what happened. I promise."
• Asking somebody to do something (Will you...?)
  • Will you please be quiet?
  • Will you shut the door, please?

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

I've tried to give her advice, but she won't listen.
The car won't start. I wonder what's wrong with it.

Shall is used in the questions "Shall I ...?/Shall we...?" to ask somebody's opinion (especially in offers or suggestions). We also use shoud in the same situations.

Shall I open the window?
Should I open the window?
Where should we have lunch?