Past tense is used to describe actions that happened before the present moment. It shows completed events in the past. On this timeline, we can see the difference between past and present actions. 'I walked' happened in the past, while 'I walk' happens now.
Regular verbs form the past tense by adding '-ed' to the base verb. For example, 'walk' becomes 'walked', 'play' becomes 'played', and 'cook' becomes 'cooked'. There are special spelling rules: verbs ending in 'e' just add 'd', some verbs double the final consonant, and verbs ending in 'y' change to 'ied'.
Irregular verbs don't follow the regular '-ed' pattern. There are three main types: verbs with no change like 'cut' to 'cut', verbs with vowel changes like 'sing' to 'sang', and completely different forms like 'go' to 'went'. These irregular forms must be memorized as they don't follow predictable rules.
Past tense is used in four main contexts. First, for completed actions like 'I finished my homework.' Second, for past habits like 'She always arrived early.' Third, for sequences of events like 'He woke up, brushed teeth, and left.' Finally, for storytelling, as in 'Once upon a time.' Each context shows actions that happened before the present moment.
Time expressions are important signals that tell us when to use past tense. Common time markers include 'yesterday', 'last week', 'ago', 'in 2020', and 'when I was young'. These expressions clearly indicate that the action happened before the present moment. For example, 'I visited my friend yesterday' or 'She traveled to Paris last week'.