If it rains, the lawn gets wet. This is called a conditional sentence because it states that something will happen if something else happens. However, the possibility of it actually happening varies—from certainty to improbability.
On the basis of the degree of possibility, conditionals are divided into different types:
- Zero conditional is used to talk about general truths and things that are always true. In zero conditional sentences, if can be replaced with when without changing the meaning. (‘’the lawn gets wet if/when it rains). Simple present tense is used in both clauses (get-rains).
- First conditional is used to talk about real and possible situations. It refers to a situation that is real and a possible condition and its probable result. In these sentences, the if clause is in the simple present (if the meeting is confirmed), and the main clauses is in the simple future (you will be informed).
- Second conditional is used to refer to a situation that is real or impossible. The sentences are not based on fact, and they refer to hypothetical condition and its probable result. In these sentences, the if clause uses the simple past (if I were the Prime Minister of India) and the main clause uses would + infinitive (I would make you my secretary). It is not important which clause comes first.
- Third conditional sentences refer to the past and describe things that didn’t happen. Thus, they are used to refer to an imaginary past condition and its probable past result. In third conditional sentences, the if clause uses the past perfect (if you had tired), and the main clause uses the perfect conditional (you could have done it).
In mixed conditional sentences, the time in the ‘if’ clause is not the same as the time in the main clause. They refer to an unreal past condition and its probable result in the present. In these sentences, the if clause uses the past perfect (if you had worked), and the main clause uses would/could/might + infinitive (you would have).