Grammar: Zero Conditional Sentences (When, Whenever)

We use the zero conditional pattern when we talk about present habits, routines, facts, and automatic effects:

The relative pronoun WHEN or WHENEVER is used:

When I go to work, I always take the train.

When I attend a meeting, I sometimes feel sleepy.

When you press the button, the door opens.

When you put butter in a hot pan, the butter melts.

When / Whenever clause	Adverbs of Frequency	Main clause
When + simple present	Never, rarely, hardly, seldom, sometimes, occasionally, often, usually, always,	Simple present
When this happens,		-- this thing happens, too.
When I go to a coffee shop, I		order Americano.
When you heat a raw egg in the microwave, it		explodes.

ADVERBS OF FREQUENCY

100%	Always	I always say “Good Morning” to my co-workers.
90%	almost always	I almost always eat eggs for breakfast.
80%	Usually	I usually take the subway to work.
70%	Frequently or often	I frequently call my best friend. I often forget to do my homework.
50%	Sometimes	I sometimes wear a hat.
40%	Occasionally	I occasionally go to the park.
20%	rarely or seldom	I rarely play games on my mobile phone. I seldom eat at fast food restaurants.
10%	Hardly ever or almost never	I hardly ever exercise.
0	Never	I never go out without money.

Examples

What is your habit when you drink coffee? = When I drink coffee, I never put sugar.

What are your habits when you are at work? = When I am at work, I am always busy.

What do you do when you celebrate your birthday? = When I celebrate my birthday, I sometimes buy a cake.

IMPORTANT REMINDERS

Rule 1: After when (and similar words like before, after, until, as soon as), we use the present tense, even if the meaning is future.

We do not usually use will after when in time clauses. Instead, we use the present simple to talk about the future.

I will call you when I arrive. (Correct)
She will text me when she gets home. (Correct)

I’ll call you when I will arrive. (Incorrect)
She will text me when she will get home. (Incorrect) 

Rule 2: We use will with when in questions about the future. (Pattern: when + will + subject + verb)

When will you come?
When will the train leave?
When will she finish her work? 

Rule 3: We can also use will with when in indirect questions (reporting or embedded questions).

In the following sentences, "when" introduces an indirect question. (Pattern: when + subject + will + verb)

I don’t know when he will arrive.
Can you tell me when they will start?

For the practice test, click this.