Zero conditionals are used to describe general truths and scientific facts where the condition and result occur simultaneously or are always true. They use the simple present tense in both the if-clause and main clause. Some examples of zero conditionals include: "If you heat ice, it melts"; "Plants die if they don't get enough water"; and "If you mix red and blue, you get purple." Zero conditionals are also used to give instructions using an imperative main clause such as "If Bill phones, tell him to meet me at the cinema."

1. ZERO CONDITIONALS
FORM/STRUCTURE
In zero conditional sentences, the tense in both parts of the sentence is the simple present.
If clause (condition) main clause (result)
If + simple present + simple present
If this thing happens that thing happens.
As in all conditional sentences, the order of the clauses is not fixed. You may have to rearrange the pronouns and adjust
punctuation when you change the order of the clauses, but the meaning is identical. In zero conditional sentences, you can
replace "if" with "when", because both express general truths. The meaning will be unchanged.
Examples
If you heat ice, it melts.
Ice melts if you heat it.
When you heat ice, it melts.
Ice melts when you heat it.
If it rains, the grass gets wet.
The grass gets wet if it rains.
When it rains, the grass gets wet.
The grass gets wet when it rains.

2. ZERO CONDITIONALS
FUNCTION/USES
The zero conditional is used to make statements about the real world, and often refers to
general truths, such as scientific facts. In these sentences, the time is now or always and the
situation is real and possible.
Example
If you freeze water, it becomes a solid.
Plants die if they don't get enough water.
If my husband has a cold, I usually catch it.
If public transport is efficient, people stop using their cars.
If you mix red and blue, you get purple.
The zero conditional is also often used to give instructions, using the imperative (command)
in the main clause.
Example
If Bill phones, tell him to meet me at the cinema.
Ask Pete if you're not sure what to do.
If you want to come, call me before 5:00.
Meet me here if we get separated.

3. FORM/STRUCTURE
If + Present Simple + Present Simple
Positive
If babies are hungry, they cry.
You get burned if you touch fire.
If I go to bed late, I wake up late.
You pay higher income taxes when you earn more money.
Negative
If you do not exercise, you gain weight.
If you exercise, you do not gain weight.
If I don’t study, I don’t do well on tests.
Questions
Does ice melt if you heat it?
When do you wake up if you have to work?
If you have to work, when do you wake up?

4. FUNCTION/USES
1. Rules
If you take your cell phone into class, it must be turned off.
If you drink alcohol, don’t drive.
Do not use a calculator when you write the test.
2. Scientific Facts and General Truths
If you heat water to 100 degrees Celsius, it boils.
If you drop something, it falls.
When you combine oil and water, they do not mix.
3. Cause and Effect
If you push the button, the volume increases.
If you close the door, it locks automatically.
The computer turns off when you disconnect the battery.
4. Routine
I wear my boots when I work.
She uses glasses when she drives.
When I cook, I use olive oil.