Hey... Which one of the following is correct :
1- they have been watching T.V for 30 mints when I got there.
2- they have watched T.V for 30 mints when I got there.

If we have no more info, which one of them would be correct?

Thanks in advance ^^

Neither one is correct in good English.

3- They had already been watching TV for 30 minutes when I got there.
4- They have watched TV for 30 minutes since I got here.

Thank you very much,,