Present perfect and past (2) - I have done and I did

This lesson explains the difference between the present perfect (I have done) and the simple past (I did). Both talk about actions in the past, but they are used in different situations.

• Present perfect links past actions to the present (results, experience, unfinished time).
• Simple past describes actions completed at a specific time in the past.
• Look for time expressions: 'yesterday', 'last week', 'in 2019' → simple past; 'ever', 'already', 'yet', 'so far', 'recently' → often present perfect.

Choose the tense depending on whether the past action is connected to the present or fixed in the past:

• Use present perfect for actions with present relevance, experience, or within an unfinished time period: I have finished the training. (result now)
• Use simple past for actions at a specific time in the past or a completed period: I finished the training last month.
• Look for time expressions: 'yesterday', 'last year', 'in 2018' → simple past; 'ever', 'already', 'yet', 'so far' → present perfect.

When in doubt, check if the sentence mentions a specific past time. If yes → simple past.

Learners often make predictable errors when choosing between present perfect and simple past. Watch for these:

• Using present perfect with specific past time expressions: 'I have finished it yesterday.' (incorrect).
• Using simple past when the result or experience is relevant now: 'I finished the report' (when you mean it affects now, prefer present perfect).
• Forgetting the auxiliary 'have' in present perfect: 'I submitted the report' vs 'I have submitted the report' (different meaning).
• Using the wrong past participle form: 'I have went' → correct: 'I have gone' or 'I went'.
• Mixing time markers that indicate unfinished vs finished periods: check 'for/since' vs 'last/ago/yesterday'.

Always check the time expression and whether the action links to the present.