Conditional Sentences: Zero, First, Second, Third — English — 3rd Year Secondary (Literary Stream) — Baccalaureate — Algerian Curriculum

Conditional Sentences: Zero, First, Second, Third

Conditional sentences (also called “if-clauses”) express a condition and its result. English has four main types of conditionals, each used for different situations: facts, real possibilities, unreal present situations, and unreal past situations.

Zero Conditional (General Truth/Fact)

Form: If + present simple, present simple.
Use: For general truths, scientific facts, and habits.

• “If you heat ice, it melts.”
• “If I am tired, I drink coffee.”

First Conditional (Real/Possible Future)

Form: If + present simple, will + base verb.
Use: For real or possible situations in the future.

• “If it rains, I will stay home.”
• “If you study hard, you will pass the exam.”
• “Unless you hurry, you will miss the bus.” (unless = if not)

Second Conditional (Unreal Present/Hypothetical)

Form: If + past simple, would + base verb.
Use: For unreal or imaginary situations in the present or future.

• “If I had a million dollars, I would travel the world.” (I don’t have a million dollars).
• “If I were you, I would accept the offer.” (“were” is used for all persons).

Third Conditional (Unreal Past)

Form: If + past perfect, would have + past participle.
Use: For unreal situations in the past — expressing regret or imaginary different outcomes.

• “If I had studied harder, I would have passed the exam.” (I didn’t study hard, I didn’t pass).
• “If they had left earlier, they would have caught the train.”

Summary Table

Type	If clause	Main clause	Example
Zero	Present simple	Present simple	If you heat ice, it melts.
First	Present simple	will + verb	If it rains, I will stay.
Second	Past simple	would + verb	If I were rich, I would travel.
Third	Past perfect	would have + V3	If I had studied, I would have passed.

For more grammar, see Conditionals Practice and Passive Voice and Relative Clauses.

Exercises

1. What type of conditional? “If I had known, I would have come.” “If it rains, we will cancel the picnic.”
2. Complete: “If I (be) you, I (apologize).” “If she (study), she (pass) the exam.”
3. Write one sentence for each type of conditional.