Present simple use
Present Simple Tense is used when we refer to the following sentences:
1. We use Simple Present to refer to events, actions or situations which are true in the present period of time and, which for all we know, may continue indefinitely.
I live in London.
Mrs Brown teaches English.
He smokes.
My father works in a bank.
My sister wears glasses.
2. The Simple Present can be used to describe habitual actions, things that happen repeatedly.
She sees him every day.
He often feels tired.
I get up at 7 a.m.
John smokes a lot.
3. We use Simple Present for statements that are always true.
Water boils at 100° C.
Cats don't fly.
Dogs bark.
Summer follows spring.
Gases expand when heated.
4. We use Simple Present when we ask or quote something from books, announcements, notices. Then we usually use the verb 'say'.
"What does the book say?" "It says, 'Cook very slowly.'"
A notice warns people not to go any further.
5. When we write headlines in newspapers.
PEACE TALKS FAIL.
PRIME MINISTER VISITS SHOE FACTORY
6. We use Present Simple in narration of events and this tense is often used by sport commentators.
All of a sudden the door opens and a stranger walks in.
Brown passes the ball to Wilson who kicks it and ... misses.
7. When we talk about planned actions, especially about timetables, schedules, TV programmes.
The train leaves in five minutes.
8. When we used verbs which aren't used in Present Progressive.
I love you.
I understand it now.
9. When we express the First Conditional.
If I see Ann I'll ask her.
If she comes, I'll call you.
10. We use Present Simple in Time Clauses.
As soon as he earns any money he will spend it.
When she comes, I'll call you.