[Grammar] Present Perfect and Past Simple

[lille82]

"I have switched off the radio." "Why did you switch it off?"
Why can`t present perfect be used in the question? Or if it can what is the difference in meaning?

 

[5jj]

"I have switched off the radio." "Why did you switch it off?"
Why can`t present perfect be used in the question? Or if it can what is the difference in meaning?

It can be used and, in this situation, there isn't a great deal of difference in meaning.

 

[lille82]

Thanks.
For some reason only the question with past simple is correct in the test book. Could you please explain the difference in other situations?

 

[emsr2d2]

Whilst the combination of the two is not incorrect and it is perfectly understandable, I must admit that I would expect to find:

I switched off the radio.
Why did you do that?

or

I have switched off the radio.
Why have you done that?

Having said that, they're both unnecessarily wordy. You would, in everyday conversation, hear:

I've switched off the radio.
Why?