Conditional clauses, subject and operator inversion, non-finite conditional clause

Conditional sentences can be introduced by IF, UNLESS, GIVEN THAT, ON CONDITION THAT, PROVIDING THAT, PROVIDED THAT, SUPPOSING THAT, ASSUMING THAT.

 Open (real) conditional sentences are based on some fact in real time and express a possible condition and its possible result.

Hypothetical (unreal) conditional sentences are not based on fact since they express a situation which is contrary to reality. This unreality is shown by a tense shift to the past.

The difference between conditions is not related to time as all can refer to the present or future. They express different states of probability/improbability.

If it rains this weekend, I will spend time studying. = it is probable the rain comes

If it rained in the Sahara, the desert would become green. = most unusual

If there is a nuclear was, we will... = said by a pessimist who thinks it will certainly come

If there was a nuclear war, we would... = the speaker sees the war actually coming as not probable.

Zero conditional

Zero conditional clause is used when we talk about scientific facts, constant laws of nature, unchangeable rules and customs. IF/WHEN can be used and both clauses are in present simple. This condition is open (real) as it can happen and does happen, being always true. It can somewhat refer to future, telling somebody else what is going to happen.

If-clause                       Main clause

present simple           present simple

When it is lunchtime in London, it is breakfast time in New York.

If you boil an egg, it becomes save to eat.

First conditional

The first condition refers to possible/probable condition in the future.

If-clause                   Main clause

present simple       will/won't +  infinitive

If it rains, the picnic will be cancelled. If it rains, I won't go out.

It can be used for threats and warnings.

If you don't study, you will not pass your exams. Unless the strike is called off, there will be problems.

If you don't go away, I will call the police. (= Go away or I'll call the police.)

Imperative can be used in the main clause.

Run away from the building if you hear the fire alarm.

Present continuous or present perfect can be used as well.

If you are reading Game of Thrones, I'll phone later.

I you have read the first volume of Game of Thrones, you will know who dies at the end.

Second conditional

The second conditional in the past tense refers to the unreal or hypothetical conditions in the present or future. The past tense distances meaning from reality.

If-clause                 Main clause

past simple           would/wouldn't +  infinitive

If had had unlimited amount of time, I would read all existing fantasy books. (unreal)

If I studied Japanese, I wouldn't have difficulties in Japan. (hypothetical future)

It can be used to give advice.

If the bookshop assistant was rude to you, I would complain to the manager.

  

Third conditional

The third conditions refers to past events that cannot be changed but we ponder "what if...?"

If-clause                     Main clause

Past perfect              would have/wouldn't have + past participle

If you hadn't listened to his spoilers, you wouldn't have found out who dies in the end of the book.

Past perfect continuous can be also used.

If you had been reading more carefully, you would have noticed that witty metaphor.

COULD HAVE and MIGHT HAVE can be also used.

If he had known the sequel to X-Men wasn't good, he might not have gone to see it.

If I had known the film is good, I could have gone to see it.

Mixed conditionals

Mixed conditionals are formed from two clauses with different time references. The if-clause can state the cause/reason and refers to the past (third conditional) with the result in the main clause referring to the present (second conditional). They often express regrets in the present for something that happened in the past.

If-clause (3rd)                                        Main clause (2nd)

If he had studied more,                        he wouldn't have difficulties with his exams.

the cause/reason in the past              result in the present

Time reference can be reversed! The if-clause or the cause/reason can refer to the present (second conditional) and the main clause of the result can refer to the past (third conditional).

If-clause (2nd)                                  Main clause (3rd)

If Peter Parker wasn't so clever, he wouldn't have invented his spider web mechanics.

present state                                   result in past

Subject and operator inversion

When the first verb in a conditional if-clause is should, were, had we can leave out IF and put the verb at the beginning of the clause. We can do this only in hypothetical formal conditions.

Had I known, I would have mentally prepared for reading the fourth volume of Game of Thrones.

It would be embarrassing, were she to find out the truth. = if she were to

Should you change your mind, no one would blame you. = If you should change your mind

Non-finite conditional clause

Non-finite conditional clause is a subordinate clause whose verb is non-finite (to-infinitive, bare infinitive, ING/ED participle, verbless). IF and UNLESS are used to introduce a non-finite conditional clause.

If consulted, I would have advised against it. Unless done, we don't go. If satisfying, we'll continue. Without me to consult you, you wouldn't be able to manage it. With them on our side, we're save.