Will and Would

G. We use 'will' to talk about the future and to say what we believe will happen, and to talk about what people want to do or are willing to do to make promises and offers.
a. 'would' is the past tense form of 'will' to talk about the past and to talk about hypotheses (things that are imagined rather than true), and for politeness.

G1. 'Will' to say what we believe will happen in the future. (e.g. We'll be late. We will have to take the train.)
a. We use 'would' as the past tense of 'will' to say what we believed would happen. (e.g. I thought I would be late ~ so I would have to take the train.)

G2. We use 'I will' or 'We will' to make offers and promises. (e.g. I’ll give you a lift home after the party. We will come and see you next week.)

G3. We use 'will' to talk about what people want to do or are willing to do. (e.g. We’ll see you tomorrow. Perhaps dad will lend me the car.)
a. to talk about what people wanted to do or were willing to do. (e.g. We had a terrible night. The baby wouldn’t go to sleep. He kept waking up and crying. Dad wouldn’t lend me the car, so we had to take the train.)
b. to talk about something that we did often in the past because we wanted to do it. (e.g. When they were children they used to spend their holidays at their grandmother’s at the seaside. They would get up early every morning and they’d have a quick breakfast then they would run across the road to the beach.)

G4. We use 'will' in conditionals with 'if' and unless to say what we think will happen in the future or present. (e.g. I’ll give her a call if I can find her number. You won’t get in unless you have a ticket.).
a. We use 'would' to talk about hypotheses, about something which is possible but not real: to talk about the result or effect of a possible situation. (e.g. It would be very expensive to stay in a hotel.)
b. in conditionals with words like 'if' and 'what if'. In these sentences the main verb is usually in the past tense. (e.g. I would give her a call if I could find her number. If I had the money I'd buy a new car. You would lose weight if you took more exercise. If he got a new job he would probably make more money. What if he lost his job. What would happen then?)
c. We use conditionals to give advice. (e.g. Dan will help you if you ask him.) Past tenses are more polite. (e.g. Dan would help you if you asked him.)

G5. will ('ll): I'll stay a bit longer. I've got plenty of time. vs. I'd stay a bit longer, but I really have to go now. (so I can't stay longer)

G6. can also use ‘would’ when you talk about things that happened regularly in the past. (e.g. When we were children, we lived by the sea. In summer, if the weather was fine, we would all get up early and go for a swim. (= we did this regularly))
a. 'would' is similar to 'used to' (e.g. Whenever Bob was angry, he would walk out of the room.)

Will have or would have

G7. We use a modal (will or would) verb with have and the past participle when we are looking back from a point in time when something will have happened or looking back from the present. (Subject + Modal + Have + Past Participle) (e.g. They will have arrived by now. By the end of the decade scientists will have discovered a cure for influenza. I will phone at six o’clock. He will have got home by then. Look at the time. The match will have started. It’s half past five. Dad will have finished work.)
a. use 'would have' in past conditionals to talk about something that did not happen. (e.g. If it had been a little warmer we would have gone for a swim.)

G8. We use a modal verb with have to refer back:
a. ~ from a point of time in the past. (e.g. We were very worried. Someone might have taken the car.)
b. ~ from the present. (e.g. It is nearly eight o’clock. They will have arrived by now.)
c. ~ from the future. (e.g. We won’t eat until they arrive. They might not have had supper.)
d. or to refer to past time. (e.g. You should have helped her when she asked.)

Phrases with Would

G9. would you ~, would you mind (not) -ing, for requests. (e.g. Would you carry this for me please? Would you mind carrying this? Would you mind not telling him that?)
a. would you like ~; would you like to ~, for offers and invitations. (e.g. Would you like to come round to morrow? Would you like another drink?)
b. I would like ~; I’d like ~ (you) (to) ~, to say what we want or what we want to do. (e.g. I’d like that one please. I’d like to go home now.)
c. I’d rather ~ (I would rather), to say what we prefer. (e.g. I’d rather have that one. I’d rather go home now.)
d. I would think, I would imagine, I'd guess, to give an opinion when we are not sure or when we want to be polite. (e.g. It’s very difficult I would imagine. I would think that’s the right answer.)

G10. use would ('d)/ wouldn't when we imagine a situation or action (= we think of something that is not real) (e.g. It would be nice to buy a new car, but we can't afford it.)
a. use would have (done) in past (= things that didn't happen) (e.g. They helped us a lot. I don't know what we'd have done (= we would have done) without their help.)
b. often use would in sentences with if (e.g. I would phone Sue if I had her number.)

G11. Somebody wouldn't do something = he/ she refused to do it. (e.g. I tried to warn him, but he wouldn't listen to me. (= he refused to listen)