What is a conditional sentence?
A conditional sentence has two parts. The if-clause gives a condition. The main clause gives the result. "If you study, you will pass." The two parts can swap places. With the if-clause first, put a comma: "If it rains, we stay in." With the main clause first, no comma: "We stay in if it rains."
The type depends on how real, or how far from real, the idea is.
Zero and first conditional (real things)
Zero: facts and rules that are always true. If + present, present. "If you mix red and blue, you get purple." You can use when instead of if.
First: a real chance in the future. If + present, will + verb. "If I finish early, I will call you." Do not put will in the if-clause.
Second conditional (imagining now)
We talk about something unreal or unlikely now or in the future. If + past, would + verb. "If I had a car, I would drive to work." The past verb here does not mean past time. It shows the idea is not real.
With be, we use were for every person: "If I were you, I would wait." This is also how we give advice.
Third conditional (imagining the past)
We talk about a past that did not happen. We cannot change it, so it is often regret or a lesson. If + had + verb3, would have + verb3. "If she had left earlier, she would have caught the bus." Meaning: she did not leave early, so she missed it.
Mixed conditionals
Sometimes the condition and the result are at different times. The common mix: If + had + verb3, would + verb, a past cause with a result now. "If I had saved money, I would be rich now." The other mix: If + past, would have + verb3, a general truth with a past result. "If he were braver, he would have spoken up."
Useful words: unless, as long as, provided that
Unless means "if not". "Unless you hurry, you will be late" = "If you do not hurry, you will be late." Do not add a second negative after unless. As long as and provided that mean "only if". "You can go out as long as you finish homework." For formal conditions, should can start the sentence: "Should you need help, call me."
Try it: make your own
Take one real thing from today. Write it in each type. Example: "I do not have a bicycle." Second: "If I had a bicycle, I would ride to school." Third: "If I had bought one last year, I would have ridden it all summer." In the 3D, pick the type and check that your sentence matches the block times.
Key formulas and definitions
- Zero: if + present, present
- First: if + present, will + verb
- Second: if + past, would + verb (if I wereβ¦)
- Third: if + had + verb3, would have + verb3
- Mixed: if + had + verb3, would + verb / if + past, would have + verb3
- unless = if β¦ not
Worked examples
1. Finish: "If you heat water to 100Β°C, it ____" (zero conditional).
Boils. A fact that is always true, so use present: "If you heat water to 100Β°C, it boils."
2. Complete: "If it ____ (rain) tomorrow, we ____ (cancel) the picnic."
First conditional: "If it rains tomorrow, we will cancel the picnic." The if-clause takes present; the result takes will.
3. Fix: "If I will see him, I will tell him."
No will in the if-clause. Correct: "If I see him, I will tell him."
4. Give advice with "if I were you" to a student who sleeps late.
"If I were you, I would sleep earlier." Second conditional with were.
5. Make a third conditional: "I missed the bus, so I was late."
"If I had not missed the bus, I would not have been late."
6. Make a mixed conditional: "I did not study medicine, so I am not a doctor now."
"If I had studied medicine, I would be a doctor now." Past condition, present result.
Common mistakes
- Using will after if: "If it will rain" is wrong. Say "If it rains".
- Using would in the if-clause: "If I would have time" is wrong. Say "If I had time".
- Using "was" in advice. Prefer "If I were you".
- Forgetting had in the third conditional: "If I studied, I would have passed" mixes types. Use "had studied".