• 3. The Third Conditional
• Lesson 11 - Conditionals

The zero conditional  is used to describe something that is always true. The two parts that make up the zero conditional sentence have the same tense: simple present .

if + present simple (conditional clause)	Present simple (main clause)
If  I mix  yellow with blue,	I get  green.
If  you draw  back the curtains,	you let   the sunlight in.

The positions of the two clauses above are not fixed. In other words, they can change places.

present simple	if + present simple
I get   green	if I mix  yellow with blue.
You let  the sunlight in	if you draw back the curtains.

When/whenever  can be used instead of if .

We can use the past simple  instead of the present simple  as above. The past simple must be used in both clauses.

• 3. The Third Conditional
• Lesson 11 - Conditionals