Four past modal structures

would have + pp

Imagined past — something that didn't happen
I would have loved to go.

should have + pp

Regret or complaint about the past
You should have told me.

needn't have + pp

Did it — but it wasn't necessary
I needn't have hurried.

didn't need to + inf

Didn't do it — correctly, as it wasn't needed
I didn't need to pay.

Should have vs Would have

should have + pp → regret or complaint

would have + pp → imagined result in a different past

You should have told me!

I regret you didn't — complaint

I should have studied harder.

Personal past regret

She would have called if she'd known.

Imagined — she didn't know

Needn't have vs Didn't need to

Both = unnecessary — but one happened, one didn't

needn't have + pp → DID it, but it was unnecessary

didn't need to + infinitive → DIDN'T do it because unnecessary

needn't have = wasted effort

I needn't have bought a ticket — it was free.

I bought one. Wasted!

didn't need to = correctly avoided

I didn't need to buy a ticket — my brother had one.

I didn't buy one. Correct!

Watch out: 'Needn't have gone' = went, but shouldn't have. 'Didn't need to go' = correctly stayed home.

Common mistakes — FCE Traps

You should went earlier

→

You should have gone earlier

should + have + past participle

I would have go if I'd known

→

I would have gone if I'd known

would have + past participle

She needn't have to buy it

→

She needn't have bought it

needn't have + pp (no 'to')

He didn't need to have gone

→

He didn't need to go

didn't need to + bare infinitive

You should of told me

→

You should have told me

It sounds like "of", but it is always have

Your turn

Answer out loud — full sentences

Use should have, would have, needn't have, didn't need to.

1

What should you have done differently last week?

2

Tell me about a time you needn't have worried.

3

What didn't you need to do last weekend?

4

What would you have done if you had had a free day yesterday?

Summary

would have + pp

Unreal/imagined past result

I would have gone.

should have + pp

Past regret / complaint

You should have told me.

shouldn't have + pp

Regret about past action

I shouldn't have eaten it.

needn't have + pp

Did it — but unnecessary

I needn't have hurried.