The present simple is used to describe facts in science, and geographical description.
- The light from the Sun takes 8 minutes 20 seconds to reach the Earth.
- The river Po flows into the Adriatic Sea.
The present simple is used to describe habitual actions. A frequency adverb is often used.
- I usually take a shower in the morning.
The present simple is used to describe the events in a narrative, when the event are summarized. It is used to describe what happens in a film or book, or in a table of events.
- In Chapter 2, Jane and Alex meets John, and agrees to go to the bookstore with him.
- George Washington becomes the first president of the USA.
The present continuous is used to describe actions which are temporary and not yet finished.
- I'm doing my homework.
The present continuous can describe a temporary habit. A time expression is necessary.
- At the moment we're sending all the mail by courier, because the Post Office is on strike.
The present continuous can describe a repeated temporary action. A time expression is necessary.
- Whenever I see Jack he's smoking.
- You're making the same mistake again!
The present continuous is used to describe an annoying habit. A frequency adverb is necessary.
- You're always borrowing money from me!
Problems with simple and continuous
Some verbs are not normally used in the continuous, because the describe activities which already extend in time. These are sometimes called ‘state' verbs.
be, believe, cost, depend, have, hear, know, matter, smell, suppose, taste, think, understand
Some of these verbs can be used in continuous forms with a change of meaning.
- I'm thinking of buying a new car. (Consider)
- I'm tasting the soup, to check if it needs more salt. (Sample)
- I'm having breakfast. (Eat)
The difference between simple and continuous can be one of attitude.
- Do you sleep a lot? (Your general habit)
- Are you sleeping enough? (Your situation at the moment)