英語の「ゼロ条件文」とは？いつ使う？
You know you can use "if" to talk about the future: "If it rains tomorrow, I will stay home."
But there is another, simpler "if" sentence for talking about facts and habits.
For example, scientific facts like: "If you heat water to 100°C, it boils."
This is correct. But is that the only time we use this grammar?
The Zero Conditional is for general truths, scientific facts, instructions, and obvious results.
It’s not just for science class. We use it every day in natural conversation.
Let's look at the simple rule and the many different situations where we use it.
The Simple Rule: How to Make the Zero Conditional
The structure is always the same and simple.
If + Present Tense , Present Tense
The comma (,) is important when the "if" part comes first.
You can use different present tenses in both parts:
If + Present Simple , Present Simple (Most common)
If the weather is good, the park is crowded.
If + Present Continuous , Present Simple
If the baby is crying, he is probably hungry.
If + Present Perfect , Present Continuous
If you have finished your work already, you are working faster than me.
The key is that both parts use a present tense. This shows the situation is always or generally true.
Why We Use It: Different Situations with Examples
1. For Scientific Facts & Universal Truths
This is the classic use. It describes things that are always true in nature or science.
If you mix red and blue, you get purple.
If plants don't get sunlight, they die.
2. For General Habits & Routines
We use it to talk about what always happens in our personal lives.
If I work late, I get a taxi home.
If my husband cooks, I wash the dishes.
3. For Instructions & Rules
It's very common in manuals, recipes, and giving clear advice.
If the red light appears, press the stop button.
If you feel unwell, tell the manager immediately.
4. For Obvious Results (Cause and Effect)
We use it when one situation always leads to a definite result.
If you touch a hot stove, you get burned.
If I drink coffee after 5 PM, I can't sleep.
5. For Giving Advice (General, Not Personal)
This is different from the Second Conditional ("If I were you..."). The Zero Conditional gives general wisdom.
If you save money every month, you build good financial habits.
If you practise English every day, you improve quickly.
Why Getting This Right Matters
Using the Zero Conditional correctly makes your English sound natural, clear, and confident.
Zero Conditional (Fact/Habit): If I eat seafood, I get sick. (This always happens to me.)
First Conditional (Future Possibility): If I eat that seafood, I will get sick. (I'm talking about this specific meal now.)
Understanding the difference helps you express facts versus predictions accurately.
Quick Practice: Zero or First Conditional?
Are these sentences Zero Conditional (general truth) or First Conditional (future possibility)?
1. If you leave ice in the sun, it melts.
2. If you leave now, you will catch the train.
3. If people don't drink water, they become dehydrated.
4. If it's sunny tomorrow, we will have a picnic.
(Remember: Zero = always true. First = a specific future possibility.)
What Not to Say: A Common Mistake
A common error is using "will" in the "if" clause for general truths.
✘ If water will reach 100°C, it boils.*
✔ If water reaches 100°C, it boils.*
Rule: Never use "will" after "if" in the Zero Conditional. Use a present tense.
Conclusion & Final Thought
The Zero Conditional (If + Present, Present) is your tool for talking about the world as it is.
It’s for facts, habits, instructions, and definite results.
It’s a practical part of everyday English for describing how things work, from science to your daily routine.
Understanding it helps you explain what always happens.
Answers to Practice:
1. Zero Conditional (A scientific fact)
2. First Conditional (A future possibility about a specific train)
3. Zero Conditional (A general truth about human biology)
4. First Conditional (A future plan based on tomorrow's weather)