These form both the PAST SIMPLE and the PAST PARTICIPLE (used in the PRESENT PERFECT), by adding -"ed" to the verb stem, e.g.:
When a regular verb ends in "y" the ending of the PAST SIMPLE AND PAST PARTICIPLE changes to "ied" .. eg carry > carried, marry > married.
Irregular verbs (also called strong verbs) change the vowel of the verb stem. swim (swam, have swum), break (broke, have broken), lead (led have led).
Other irregular verbs add the letters "d" or "t" and also change the vowel sound - hear (heard, have heard) , sweep (swept, have swept).
A fairly large class of verbs which already end in "d" or "t" do not change in their past forms - bet (bet, bet), broadcast, burst, cut, cast, fit, forecast, hit, hurt, put, quit, reset, read, shed, shut, wed.
"Did" to make questions about the past but using the main verb in the naked INFINITIVE form:
But some questions are also made using the simple past:
We use didn’t (did not) to make negatives with the past tense:
1. Something that happened once in the past:
2. Something that happened again and again in the past:
3. something that was true for some time in the past:
4. we often use phrases with ago with the past tense:
You must always use the Present perfect when the time of an action is not important or not specified.
You must always use the Simple past when details about the time or place that an action occurred are given or requested.
You can also use "used to" to describe a habit in the past - often in contrast with what you do now e.g.