Simple Present Tense
A tense formed by using the verb stem, which is followed by "s" in the third person singular.
Uses and examples:
1. Present feeling and thought : I feel rather sick.
2. Actions or states that are true now but have no particular reference to time : He lives in London.
3. Timeless truths : Fairly pure water freezes at about 0 degree Celcius.
4. Habitual actions : Nearly a quarter of men clean out their cars once a month.
5. Open conditionals : If I see anything wrong, i'll ring you later from my surgery.
6. Scheduled future actions : The following day, we travel to Berlin.
7. Newspaper headlines : Ministers flout arms sales code.
8. Informal narrative : And he says to her, "what did you do before you joined the police?"
9. Retelling a story : Enter the Hero, who then fights it out with the baddies.
10. In sports commentaries : In it goes, but it's too strong for Hasselbaink.

Simple Past Tense
A tense used to refer to actions in the past. In regular verbs, it is formed by adding -ed to the verb stem (or just -d if the verb stem ends in e).
Uses and examples:
1. To refer to a single action in the past : On 25 May 1812 the Felling pit in Durham exploded, killing 92 men and boys.
2. To refer to a regular or repeated action in the past : They met several times last week; The mobile shop called once a week.