Conditional Sentences with if｜Basic Rules and Example Sentences

In English, when I want to express conditions such as “If ~, then …”, I use conditional sentences with if.

This basic structure is widely used in contexts ranging from daily conversation to business. Depending on the situation, the expression changes—for example, when talking about the future, making hypothetical statements contrary to reality, or imagining a past that did not happen.

In this lesson, I will organize the basic rules of the if-structure and the three main types of conditional sentences, and explain how to use them in a clear way.

1. Basic Rules of Conditional Sentences with if

The word if means “if/when” and functions mainly as a conjunction linking two clauses.

Basic Structure: If + subject + verb, subject + verb …

A conditional sentence has an if-clause (expressing the condition) and a main clause (expressing the result). These two clauses are usually separated by a comma. The if-clause can appear either at the beginning or in the middle of the sentence.

Conditional sentences are broadly divided into three types:

I will now explain each type in detail.

2. Conditional Sentences for Future Possibility (Realistic Conditions)

Structure: If + present tense, subject + will + base verb

This is the most basic form, used when talking about something that may realistically happen.

In this example, the condition is based on a realistic possibility: it might rain tomorrow.

Important Rule: Even when referring to the future, I must use the present tense in the if-clause, not will.

3. Subjunctive Past (Unreal Conditions in the Present)

Structure (Subjunctive Past): If + past tense, subject + would + base verb

This type of conditional sentence is used to describe a hypothetical situation contrary to the present reality, often translated as “If ~, … would …”.

In reality, I do not have much money, so I cannot travel.

Special Rule: In the subjunctive past, the verb be is usually expressed as were for all subjects, even with the first person singular “I”.

4. Subjunctive Past Perfect (Unreal Conditions in the Past)

Structure (Subjunctive Past Perfect): If + had + past participle, subject + would have + past participle

This form is used to describe a hypothetical situation contrary to a past fact, meaning “If ~ had …, … would have …”.

This implies that in reality, she did not study hard enough, so she failed the exam.

5. Summary

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「English Morning｜基礎から学ぶ英語講座」を運営している泉（Izumi）です。このサイトでは基礎から応用まで、英語の文法を解説しています。