2 ZERO CONDITIONALTo generalize or give facts (If you heat water, it boils)To talk about something which is always true or always happens as a result or something else, use if + present simple and the present simple in the other clause. You can also use the present continuous or present perfect in either clause.If you want to be fit, you have to have a healthy diet.If your muscles ache every day, you are probably doing too much exerciseIf you haven’t been to London, you haven’t lived.Although zero conditionals are usually based on present tenses, they can also be used in the past (If people didn’t have money, they didn’t eat that day).
3 FIRST CONDITIONAL If you haven’t done your exercises yet, do them now! You can use any present tense in the if clause (present simple, continuous, perfect) and any future form (will, going to, future perfect, future continuous) or an imperative in the other clause.If you haven’t done your exercises yet, do them now!If the photos are good, I´ll send them to you.If you are not going, I’m not going to go either.Remember that although a present tense is used after if, the meaning is future.
4 FUTURE TIME CLAUSEWhen you are talking about the future, use a present tense after these expressions: when, as soon as, until, unless, before, after, in case. This can be any present tense (present simple, present continuous, present perfect)I´ll be ready as soon as I’ve had a shower.We´ll probably be having dinner when you arrive.We´re not going to go out until the rain has stopped.Take your umbrella in case it rains.
5 A future tense can never be used after if or after when, as soon as, until, unless, before, after, in case. Typical mistakes:I´ll be ready as soon as I’ll have had a shower (X)We´ll probably be watching the cup final when you’ll be arriving (X)We use “in case” when we do something in order to be ready for future situations/problems. Compare the use of “if” and “in case”.I’ll take a jacket if it´s cold = I won´t take one if it´s not coldI’ll take a jacket in case it´s cold = I’ll take a jacket anyway because it might be cold.Do not confuse in case with in case of (In case of fire, break the glass). “In case” can also be used in the past tense (I took a jacket in case it was cold).