1st & 2nd Conditional

Use the zero conditional for things that are always or generally true: scientific facts, rules and habits. Whenever the condition happens, the result happens too: 'If you heat ice, it melts.' 'If I drink coffee after 6 pm, I can't sleep.'

Form: If + present simple, present simple. Both clauses use the present simple.

In the zero conditional, 'if' means almost the same as 'when' or 'whenever': 'If/When you press this button, the machine stops.'

For instructions, the result clause can be an imperative: 'If the alarm rings, leave the building.'

Use the first conditional for a real possibility in the future and its likely result. The speaker thinks the situation could easily happen: 'If it rains tomorrow, we'll have the picnic indoors.'

Form: If + present simple, will/won't + infinitive. Even though the if-clause is about the future, it uses the present simple, not 'will': 'If I see Anna, I'll tell her' (not 'If I will see Anna').

The clauses can go in either order. Use a comma when the if-clause comes first; no comma is needed when it comes second: 'We'll miss the train if we don't hurry.'

Instead of 'will', the result can use another modal or an imperative: 'If you finish early, you can go home.' 'If you see Tom, tell him to call me.'

The first conditional is common for promises, warnings and threats: 'If you touch that, you'll burn yourself!'

'Unless' means 'if … not' or 'except if'. It is followed by a positive verb: 'You won't pass unless you study' = 'You won't pass if you don't study.' Don't add another negative: 'unless you study', not 'unless you don't study'.

'As long as' (also 'provided that' and 'providing') means 'only if' — it states a necessary condition: 'You can borrow my car as long as you drive carefully.'

'If' or 'when'? Use 'if' for something that may or may not happen, and 'when' for something you are sure will happen: 'If I see Anna, I'll tell her' (maybe I won't see her). 'When I see Anna, I'll tell her' (I'm going to see her).

Like 'if', these words are followed by the present simple when they refer to the future: unless it rains, as long as you're careful, when I get home. The same is true after as soon as, before, after and until: 'I'll call you as soon as I land.'

Use the second conditional for situations that are imaginary, impossible or unlikely now or in the future, and their imagined results: 'If I had more free time, I'd learn the guitar' (but I don't have much free time). 'If I won the lottery, I'd travel the world' (but I probably won't win).

Form: If + past simple, would/wouldn't + infinitive. The past tense here does not refer to the past — it shows that the situation is unreal. 'If I had a car' is about now.

With 'be', 'were' can be used for all persons, and it is preferred in formal English and exams: 'If she were here, she would know what to do.' 'If I/he/she was…' is common in informal speech.

You can use 'could' or 'might' instead of 'would': 'could' = would be able to; 'might' = would perhaps. 'If I spoke Spanish, I could work in Madrid.'

As in the first conditional, there is no 'would' in the if-clause: 'If I knew the answer, I'd tell you' (not 'If I would know').

The difference between the first and second conditional is not about time — both can refer to the future. It is about how likely the speaker thinks the situation is.

First conditional: the situation is real and possible. 'If I get the job, I'll move to London' (I've had the interview and I have a good chance). Second conditional: the situation is imaginary, impossible or very unlikely. 'If I got the job, I'd move to London' (I don't really expect to get it).

The same idea can be first or second depending on the speaker's view. 'If it snows tomorrow, we'll go skiing' (snow is forecast). 'If it snowed tomorrow, we'd go skiing' (it's July!).

For situations that are impossible now, only the second conditional works: 'If I lived in Japan, I'd eat sushi every day' (but I live in Spain).

Don't mix the two patterns: 'If I have time, I'll help' or 'If I had time, I'd help' — not 'If I have time, I'd help'.

'If I were you, I'd…' is a very common way to give advice. You imagine yourself in the other person's situation: 'If I were you, I'd talk to your manager.' The negative advises someone not to do something: 'If I were you, I wouldn't sign the contract yet.'

Use 'were' in this phrase, not 'am'. 'If I was you' is heard in informal speech, but 'If I were you' is the standard form, so use it in exams and writing.

The if-clause is often left out when the situation is clear: 'I'd take the job.' 'I wouldn't worry about it.'

The second conditional also makes requests and suggestions more polite and less direct: 'Would it be OK if I left early today?' 'It would be great if you could help me.'