Conditional

Conditional: Always true

If I work late, I get tired.

If the water is boiling/has boiled, it means the food is nearly ready.

Form: If present, present

States a fact, which is always true.

Conditional I

If I find her address, I'll send her an invitation.

I will send her an invitation if I find her address. (notice: no comma)

Form: If + Simple Present, will-Future

Conditional I refer to a future event. The condition is likely to be fulfilled.

when can be used instead of if to signal that it is not a question if it will happen but rather when it will happen.

Conditional II

If I found her address, I would send her an invitation.

I would send her an invitation if I found her address.

If I had the money, I could help you. (with the modal verb "can")

Form: If + Simple Past, Conditional I (would + Infinitive)

The conditional II is used when referring to a situation in the present, which would be possible, if things were differently. Like "would would happen if ..."

With modal verbs

If you get wet, you should change your clothes immediately.

If you come early, we can discuss the problem together.

A conditional II sentence can be used with either should or can when referring to the present.

Conditional: Past event with results in the present

If Jim hadn't missed the plane, he would be here now.

Form: If + past perfect, Conditional I (would + Infinitive)

If an event in the past had happened, then would have a result in the p

Conditional III

If I had found her address, I would have sent her an invitation (but I hadn't found it...).

I would have sent her an invitation if I had found her address.

If you hadn't reminded me, I might have forgotten.

Form: If + Past Perfect , Conditional II (would have + participial)

The conditional III is used to refer to past situations. An action could have happened in the past if a certain condition had been fulfilled.

When

When can also be used in a condition.

When I was young, there were no houses here. (in the past)

Nobody spoke when she came in to the room. (in the past)

When you start the engine, there's a strange noise. (in the present)

When the new park opens, I will go there every day. (in the future, like conditional I)

When I have finished my homework, I'm going to phone Marita. (in the future)