The Zero Conditional in English
Use the zero conditional to talk about things that are always true — facts, rules, and cause-and-effect. Both clauses stay in the present simple: "If you heat ice, it melts." There's no 'will' anywhere, because nothing is being predicted; you're stating a general truth. When the meaning is a rule or general fact, you can swap 'if' for 'when' with no change in meaning: "When the light is red, you stop."
Examples
- If you heat ice, it melts. heating ice always causes melting
- If I'm tired, I go to bed. a habitual cause and effect
- When the light is red, you stop. a rule; 'when' = 'if' here
The full lesson
Everything in the video, in text.
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If you heat ice, it melts. That tiny sentence hides the simplest conditional in English — and the easiest one to get wrong.
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We use the zero conditional for things that are always true: facts, rules, and cause and effect. Here's the whole pattern in one line.
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Both halves stay in the present simple. The if part is the condition; the other part is the result that always follows. No future, no will — because this is timeless.
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Start with a fact of nature. Heating ice always causes it to melt — so both verbs are present. If you heat ice, it melts.
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It works for personal habits too — a cause and effect that's true for you every time. If I'm tired, I go to bed.
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Here's the handy trick: in the zero conditional, you can swap if for when and the meaning doesn't change. When the light is red, you stop.
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It's perfect for instructions and rules, where the result is guaranteed every single time. If you press this button, the machine stops.
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Now the big trap. Don't add will. The zero conditional stays entirely in the present — will belongs to the first conditional, which is about one future moment, not a general truth.
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One more nuance: the order is flexible. Put the result first and the if part second, and you simply drop the comma.
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So remember: for things that are always true, keep both verbs in the present, and feel free to use when instead of if.