Present perfect and past (1) - I have done and I did

This lesson explains the difference between the present perfect (have/has + past participle) and the simple past. Both forms refer to actions in the past, but they are used in different situations and with different time expressions.

• Present perfect: have/has + past participle (I have done). Used for experiences, actions with present relevance, or actions that started in the past and continue to the present.
• Simple past: past form of the verb (I did). Used for actions completed at a specific time in the past.
• Look for time expressions: 'yesterday/last year/in 2010/ago' → simple past. 'ever/never/just/already/yet/since/for' → present perfect.

Use the present perfect when the action is connected to the present or when no specific past time is mentioned. Use the simple past when the action happened at a definite time in the past.

• Present perfect: have/has + past participle → focus on result or experience (e.g., 'I have seen that film').
• Simple past: verb in past form → focus on when it happened (e.g., 'I saw that film last week').
• If you give a specific past time (yesterday, last month, in 2015, two days ago) use simple past.

If in doubt, check the time expression: specific time → past simple; no specific time or connection to now → present perfect.

Watch out for these frequent errors when choosing present perfect or simple past:

• Using present perfect with a specific past time: 'I have seen him yesterday.' (Incorrect) — use simple past.
• Using simple past when the action connects to the present: 'I met the client three times this year.' (If the year is not finished, present perfect is often better.)
• Forgetting the past participle after have/has: writing 'have went' instead of 'have gone'.
• Mixing time expressions that require different tenses in the same sentence.

Focus on the time expression and whether the action has present relevance.