| Type 0 (general truths) The first type of pattern describes things that are generally true, for example habits, tendencies and facts. In this case, the tense in both clauses is usually present. If can be replaced by when if the event is highly probable, or as soon as to express immediacy between the events. unless expresses a negative condition. In many universities, if students plagiarize, they face disciplinary action. When my mum refuses to talk to my dad, he gets angry Unless deadlines are imposed on students, they tend not to accomplish academic tasks. |
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Type 1 (likely situations) The second type of pattern describes events that are viewed as likely or probable The structure is usually if + present simple and will (and other modals) or going to + bare infinitive. The order of the two clauses is usually interchangeable without much change in meaning. If can be replaced by when if the event is highly probable, or as soon as to express immediacy between the events. unless expresses a negative condition. As soon as my acne goes away, I am going to ask Cindy out on a date When taxi fares increase, I will stop taking them. Unless my GPA improves, I might not get into Harvard |
| Type 2 (unlikely or unreal events)
Unreal conditionals describe unreal , unlikely, or hypothetical situations The structure is usually if + past simple and would (and other modals) + bare infinitive. In the if clause BE usually changes to were for all persons, especially in formal writing or speech. If I won a lot of money I could afford to buy a small flat in Hong Kong. Where might you live if you could live anywhere in the world? Were Hong Kong to legalize Gay marriage, the marriage registration office might become very busy The past tense is used to show a distance from reality. |
| Type 3 (unreal past conditionals)
Unreal Past conditionals describe unreal situations in the past. The structure is usually if + past perfect and would (and other modals) + present perfect (e.g. have done). Apple would not have been so successful if Steve Jobs had not returned as CEO in 1997 She might have finished the exam if she had had more time. We can also write the above examples like this: Had Steve Jobs not returned as CEO in 1997, Apple would not have been so successful. Had she had more time, she might have finished the exam. This is known as ‘inversion with had’. |
| Mixed conditionals
Mixed conditionals are sentences in which the two clauses may refer to different time periods. If Hong Kong had not returned to China in 1997, it would be a very different place today. The if- clause refers to an unreal situation in the past, whereas the main clause refers to an unreal situation in the present. Each clause of mixed conditional sentences exhibits the grammar outlined in conditionals 0, 1, 2 and 3 above. |
