Would

Would is an auxiliary verb, a modal auxiliary verb. We use would mainly to:

• talk about the past
• talk about the future in the past
• express the conditional mood

We also use would for other functions, such as:

• expressing desire, polite requests and questions, opinion or hope, wish and regret...

Structure of Would

subject + would + main verb

The main verb is always the bare infinitive (infinitive without "to").

	subject	auxiliary verb	main verb
+	She	would	like	tea.
'd
-	She	would not	like	whisky.
wouldn't
?	Would	she	like	coffee?

Notice that:

• Would is never conjugated. It is always would or 'd (short form).
• The main verb is always the bare infinitive.

The main verb is always the bare infinitive. We cannot say:
I would to like coffee.

 

Be careful! Would and had have the same short form 'd :
He'd finished. (He had finished.)
He'd like coffee. (He would like coffee.)

Use of Would

would: Talking about the past

We often use would as a kind of past tense of will or going to :

• Even as a boy, he knew that he would succeed in life.
• I thought it would rain so I brought my umbrella.

Using would as as a kind of past tense of will or going to is common in reported speech:

• She said that she would buy some eggs. ("I will buy some eggs.")
• The candidate said that he wouldn't increase taxes. ("I won't increase taxes.")
• Why didn't you bring your umbrella? I told you it would rain! ("It's going to rain.")

We often use would not to talk about past refusals:

• He wanted a divorce but his wife would not agree.
• Yesterday morning, the car wouldn't start.

We sometimes use would (rather like used to ) when talking about habitual past behaviour:

• Every weekday my father would come home from work at 6pm and watch TV.
• Every summer we'd go to the seaside.
• Sometimes she'd phone me in the middle of the night.
• We would always argue. We could never agree.

WOULD for Past Habit

would: Future in past

When talking about the past we can use would to express something that has not happened at the time we are talking about:

• In London she met the man that she would one day marry.
• He left 5 minutes late, unaware that the delay would save his life.

would: Conditionals

We often use would to express the so-called second and third conditionals:

• If he lost his job he would have no money.
• If I had won the lottery I would have bought a car.

Using the same conditional structure, we often use would when giving advice:

• I wouldn't eat that if I were you.
• If I were in your place I'd refuse.
• If you asked me I would say you should go.

Sometimes the condition is "understood" and there does not have to be an "if" clause:

• Someone who liked John would probably love John's father. (If someone liked John they would probably love John's father.)
• You'd never know it. (for example: If you met him you would never know that he was rich.)
• Why don't you invite Mary? I'm sure she'd come.

Although there is always a main verb, sometimes it is understood (not stated) as in:

• I'd like to stay. | I wish you would. (would stay)
• Do you think he'd come? | I'm sure he would. (would come)
• Who would help us? | John would. (would help us)

would: Desire or inclination

• I'd love to live here.
• Would you like some coffee?
• What I'd really like is some tea.

would: Polite requests and questions

• Would you open the door, please? (more polite than: Open the door, please.)
• Would you go with me? (more polite than: Will you go with me?)
• Would you know the answer? (more polite than: Do you know the answer?)
• What would the capital of Nigeria be? (more polite than: What is the capital of Nigeria?)

would: Opinion or hope

• I would imagine that they'll buy a new one.
• I suppose some people would call it torture.
• I would have to agree.
• I would expect him to come.
• Since you ask me I'd say the blue one is best.

would: Wish

• I wish you would stay. (I really want you to stay. I hope you will stay.)
• They don't like me. I'm sure they wish I'd resign.

Note that all of these uses of would express some kind of distance or remoteness:

• remoteness in time (past time)
• remoteness of possibility or probability
• remoteness between speakers (formality, politeness)

would: Presumption or expectation

• That would be Jo calling. I'll answer it.
• We saw a police helicopter overhead yesterday morning. | Really? They would have been looking for those bank robbers.

would: Uncertainty

• He would seem to be getting better. (less certain than: He seems to be getting better.)
• It would appear that I was wrong. (less certain than: It appears that I was wrong.)

would: Derogatory

• They would say that, wouldn't they?
• John said he didn't steal the money. | Well, he would, wouldn't he?

would that: Regret (poetic/rare) - with clause

This rare, poetic or literary use of would does not have the normal structure:

• Would that it were true! (If only it were true! We wish that it were true!)
• Would that his mother had lived to see him become president.

 

http://www.englishclub.com/grammar/verbs-modal-would.htm