Second conditional sentences are useful for expressing outcomes that are completely unrealistic or will not likely happen in the future. Notice the correct way to structure second conditional sentences is to use the simple past tense in the if-clause and an auxiliary modal verb (e.g., could, should, would, might) in the main clause (the one that expresses the unrealistic or unlikely outcome). The following sentences illustrate a couple of the common mistakes people make when using the second conditional:

Incorrect If I inherit a billion dollars, I would travel to the moon.

Correct If I inherited a billion dollars, I would travel to the moon.

Explanation: when applying the second conditional, use the simple past tense in the if-clause.

Incorrect If I owned a zoo, I will let people interact with the animals more.

Correct If I owned a zoo, I might let people interact with the animals more.

Explanation: use a modal auxiliary verb in the main clause when using the second conditional mood to express the unlikelihood that the result will actually happen.

Another Example: - If I were him, I would buy an expensive car. - If I saw a car accident, I would call an ambulance. - If I were you, I will move to London.

4. Third Conditional Sentences Third conditional sentences are used to explain that present circumstances would be different if something different had happened in the past. These sentences express a condition that was likely enough, but did not actually happen in the past. These are all conditions that were likely, but regrettably did not happen. Note that when using the third conditional, we use past perfect (i.e., had + past participle)) in the if-clause. The modal auxiliary (would, could, should, etc.) + have + past participle in the main clause express the theoretical situation that could have happened. Consider these common mistakes when applying the third conditional:

Incorrect If you would have told me you needed a ride, I would have left earlier.

Correct If you had told me you needed a ride, I would have left earlier.

Explanation: with third conditional sentences, do not use a modal auxiliary verb in the if-clause.

Incorrect If I had cleaned the house, I could go to the movies.

Correct If I had cleaned the house, I could have gone to the movies.

Explanation: the third conditional mood expresses a situation that could have only happened in the past if a certain condition had been met. That’s why we use the modal auxiliary verb + have + the past participle.

Another Example: - If he had talked to me, I would have listened to him. - If it had rained last weekend, we would have stayed at home. - If she had found his phone number, she might have called him for the party.

Exceptions and Special Cases When Using Conditional Sentences As with most topics in the English language, conditional sentences often present special cases in which unique rules must be applied.

Use of the Simple Future in the If-Clause. Generally speaking, the simple future should be used only in the main clause. One exception is when the action in the if-clause will take place after the action in the main clause.

Example: If aspirin will ease my headache, I will take a couple tonight.

Explanation: The action in the if-clause is the aspirin easing the headache, which will take place only after the speaker takes them later that night.

“Were to” in the If-Clause The verb phrase were to is sometimes used in conditional sentences when the likely or unlikely result is particularly awful or unthinkable. In this case, were to is used to place emphasis on this potential outcome.

Example: - If I were to be sick, I would miss another day of work. - If she were to be late again, she would have to have a conference with the manager. - If the rent were to have been a penny more, they would not have been able to pay it. Note that the emphatic “were to” can be used to describe hypothetical scenarios in the present, future, and past.

Punctuating Conditional Sentences Despite the complex nature of conditional sentences, punctuating them properly is really simple! Here’s the skinny:

Use a comma after the if-clause when the if-clause precedes the main clause.

Example: If I’d had time, I would have cleaned the house.

If the main clause precedes the if-clause, no punctuation is necessary.