IF Sentences (1st and 2nd conditionals)

1) We use the first conditional (if + verb in present simple) to talk about a possible future action or situation. The IF CLAUSE is often followed by a main clause with WILL / WON'T. If the weather gets better, we'll go for a walk. (Not: If the weather will get better) or We'll go for a walk if the weather gets better.

2) In addtion to the futureWILL, we can also use CAN; SHOULD; OUGHT TO; MAY; MIGHT; MUST or an IMPERATIVE in the main clause. If you want to go to London, you can catch a bus. / We souldn't be late, if the train is on time. / Phone me if you want anything.

3) To talk about something that's always true, we use IF + PRESENT SIMPLE + PRESENT SIMPLE. If you heat plastic, it mealts. / If I travel by car, I always get carsick.

4) We use the 2nd conditional IF + VERB IN PAST SIMPLE + WOULD / WOULDN'T, COULD, MIGHT to talk about an action or situation in the present or the future which is improbable, hypothetical or imaginary. If public trasport was better, there would be fewer cars on the road.  / You might feel better if you took some of these tablets. / If you found $100 in the street, what would you do with it?