Here is favorite trick question I like to ask people in my writing classes:
If you were writing to your manager about completing an assigned task, which is sentence correct: I completed the task or I have completed the task?
The answer: Both are correct. It depends on the impression you want to give your manager. Let me explain why I prefer I have completed the task.
The first sentence, I completed the task, is in the simple past tense, indicating a past action; the second sentence, I have completed the task, is in the present perfect, indicating an action started in the past and just completed. I would want my manager to know that I haven't wasted a moment from the time of completing the task to the time of alerting her about it. That's the value of the present perfect: its immediacy.
Think of the importance of reporting to management in the present perfect tense in these cases:
- I have started the investigation.
- You have used an expired password.
- The client has contacted me about her concern.
