What were you doing all day yesterday?
What did you do all day yesterday?
If I understand right, both sentences are correct but there are some differencies in their meaning.
- We use Past Continious when we want to emphasize that the process isn't finished. But how can we know that if we don't know what they do? I don't understand that.
- For my opinion, Past Simple is best choice if we don't know what work/sport activity/relaxation can be done by that person yesterday. Am I right?
- If the sentence would be "What ... you ... at the specific time?", I would use Past Continious because we certainly know that the action isn't finished. For example, "What were you doing at 7 o'clock yesterday?" or "What were you doing yesterday when I called you?" I hope that it's correct understanding.
- From the internet: "the difference between the past continuous and simple past when they have no other information attached to them is sometimes very subtle in English and not easy to explain to a learner. Especially because (as with so much in English grammar) we often ignore the rules. For example: a mother comes home and sees rubbish all over the house. She says to her son "The house is a complete mess! What were you doing here yesterday?!" Unfortunately it means (in practical terms) almost the exact same thing as "The house is a complete mess! What did you do here yesterday?!" What she wants to know is simply what happened." <--- If I understand right, the correct answer here would be with Past Simple "What did you do here yesterday?!" because of the action is finished.
- An interesting example from the internet: "What were you doing when he started shouting at you? (Asking what the person was in the middle of doing just before he started shouting.) What did you do when he started shouting at you? (Asking how the person reacted when he started shouting.)"
If you can, please write some examples that may help to explain the difference in detail in their usage.