Conditional sentences express a particular “condition” and the “result” of that condition. The conditional clause begins with if, while the result clause begins with will, would, or would have. Non-native English speakers can find conditional sentence challenging because English has specific rules for how you can and cannot expresses a particular type of condition. The verb tenses and forms that can be used change depending on whether the condition being expressed is true or untrue and whether it occurs in the past, present, or future.
In this lesson, we’re going to cover the basics of conditional sentences. We’ll also look at some of the more advanced uses of conditionals. Next time we’ll finish conditionals and discuss a related subject, expressing wishes.
Expressing True Situations in the Present or Future
Conditional sentences that express true situations in the present or future are made by combining a simple present tense if-clause with a result clause consisting of will + simple form verb. A “true in the present or future” conditional sentence can have various possible verb forms. Note that the if-clause verb is always simple present, even when the result clause verb is future tense. Also note that there is no such thing as a “true to fact” past tense conditional sentence in the English language. Such a sentence would make neither grammatical nor logical sense.
A simple present result clause expresses an activity or situation that is habitually or regularly true:
If I don’t leave home by seven o’clock, I always arrive late at work.
Using the simple present OR the simple future in the result clause can help express an established pattern, predicable fact, or general truth:
Water boils/will boil if the temperature reaches 212°F/100°C.
The simple future in the result clause can also be used to express a particular future situation:
If I don’t leave work by six o’clock tomorrow, I will miss the beginning of the movie.
Modals and phrasal modals (which we covered in earlier lessons) can be used as part of the result clause to help express the speaker’s attitudes about the result:
If it snows, I should work from home.
If it snows, I might decide to work from home.
If it snows, I can’t go to work.
If it snows, I’m going to stay home.
An imperative verb can be used in the result clause as well. The speaker is essentially ordering someone make the result “come true” if or when the stated condition occurs:
If anyone arrives for an interview, please send them to the conference room.
Including should as part of the if-clause expresses a degree of uncertainty about the truthfulness of the condition. The meaning of the following example is almost the same as the previous one. However, the speaker is not absolutely certain that anyone will show up for the interview:
If anyone should arrive for an interview, please send them to the conference room.
Untrue (Contrary to Fact) Conditions in the Present or Future
When expressing an idea that is untrue in the present or future, use the simple past form of a verb in the if-clause. The result clause is constructed of would + simple form. This type of conditional sentence is equivalent to saying, “In truth, X condition is not true”:
If I owned this store, I wouldn’t offer refunds.
In truth, I don’t own this store.
If James weren’t on vacation, he would handle this.
In truth, James can’t resolve the current situation because he is on vacation. Note that were/were not/weren’t should be used in the if-clause even when the subject is singular. While was/was not/wasn’t is sometimes used in casual conversation, this is not grammatically correct:
If I were you, I would accept the settlement offer. (Formal: grammatically correct)
If I was you, I’d take the deal. (Informal: grammatically incorrect)
Would vs. Could
Using would in a conditional sentence expresses desired or predictable results. Using could expresses possible options:
If I won the lottery, I would retire.
I plan to retire in the unlikely event that I win the lottery.
If I won the lottery, I could retire.
Winning the lottery would make it possible for me to retire.
Expressing Untrue Conditions in the Past
Untrue conditions in the past are expressed by combining a simple past if-clause with a result clause made from would have +past participle. This type of conditional sentence is equivalent to saying: “in fact, X fact was untrue.” In other words, a past untrue conditional sentence refers explicitly to conditions and results that have already occurred:
If she had taken summer classes, she would have graduated early.
In truth, she did not take summer classes. Therefore, she did not graduate early.
If Casey hadn’t tackled another player during the soccer match, she wouldn’t have received a red card.
In truth, Casey received a red penalty card because she attacked another player during a soccer game.
Progressive Verb Forms and Conditional Sentences
Progressive verb forms can be used in conditional sentences. A progressive tense verb is used in a progressive situation, just as it would be if the sentence were a statement of fact:
It is snowing right now, so I will not drive to work.
If it were snowing right now, I would not drive to work.
It was snowing yesterday, so I did not drive to work.
If it had not been snowing yesterday, I would have driven to work.