This is used to talk about the probable consequences of possible future actions or situations. The basic form of the First Conditional is:
If + Present Simple (= if clause), will + infinitive (=main clause). E.g.
If we don’t deliver this order on time, we will lose the contract.
How long will it take if we go by car?
Imperative forms and modal verbs can also be used in the main clause. e.g.
If she rings, tell her I´ll call her later.
If there’s time, I might do some sightseeing.
Note in conditional sentences, the if clause can be the first or second clause.
If it is in first position, the if clause is followed by a comma.
3.2 second conditional
The basic form is: if + Past Simple, would + infinitive. It is used:
When the idea expressed in the if clause is possible but not thought so likely to happen as in a First Conditional situation.
If they offered me promotion, I would take it.
If I didn’t go to the meeting, would it be a big problem?
When the idea in the if clause is contrary to what is known to be true e.g.
If had my car, I´d give you a lift. (but I haven´t got my car).
If I didn’t like my job, I´d leave(but I do like my job).
In the phrase if I were you to give advice e.g.
If I were you, I´d have a word with the manager.
(Note were is frequently used with I/we as an alternative to was)
3.3 First vs. Second Conditional
When the if clause refers to a situation which is possible in the future, the choice of conditional indicates how likely the speaker thinks it is to happen. The choice is therefore determined by the context. E.g.
If interest rates go up, we´ll be in trouble.
If interest rates went up, we´d be in trouble.
Note the first sentence indicates that there has probably already been speculation about interest rates going up and that a decision is expected quite soon. The second sentences is much more hypothetical. It might be used in a discussion about whether it would be a good idea to borrow some money.
3.4 Unless, providing, provided, in case
Unless can be used instead of if… not with present and future meaning. e.g.
Unless you call, we´ll assume you´ll be arriving around 8.
= if you don’t call…
Note if … not is preferred in threats and warnings. e.g.
If you’re not careful, you’ll break it.
If you don’t reply within 14 days, we´ll take legal action.
Providing/ provided can be used instead of if with present and future meaning when new want to emphasize the condition. e.g.
Providingeverything runs smoothly, we´ll be able to reach our target.
Provided the machine doesn´tbreak down, the order will be ready on time.
In case + Present Simple is used when we take action in advance to avoid a problematic situation in the future. e.g.
We´d better reserved a table in case the restaurant is busy.
Compare we´ll leave early in case there´s a lot of traffic.
With we´ll turn off the tomorrow if there´s a lot of a traffic.
In the first sentences in the action (leave early) will take place before the situation in the in case clause (there´s a lot of traffic). In the second sentence the action (turn off the motorway) will only take place if the situation happens (i.e. there is a lot of traffic).