I could tune you could tune he could tune we could tune you could tune they could tune
V-ing form
I could be tuning you could be tuning he could be tuning we could be tuning you could be tuning they could be tuning
Perfect
I could have tuned you could have tuned he could have tuned we could have tuned you could have tuned they could have tuned
V-ing perfect
I could have been tuning you could have been tuning he could have been tuning we could have been tuning you could have been tuning they could have been tuning
Negation
Simple form
I could not tune you could not tune he could not tune we could not tune you could not tune they could not tune
V-ing form
I could not be tuning you could not be tuning he could not be tuning we could not be tuning you could not be tuning they could not be tuning
Perfect
I could not have tuned you could not have tuned he could not have tuned we could not have tuned you could not have tuned they could not have tuned
V-ing perfect
I could not have been tuning you could not have been tuning he could not have been tuning we could not have been tuning you could not have been tuning they could not have been tuning
Interrogative form
Simple form
could I tune? could you tune? could he tune? could we tune? could you tune? could they tune?
V-ing form
could I be tuning? could you be tuning? could he be tuning? could we be tuning? could you be tuning? could they be tuning?
Perfect
could I have tuned? could you have tuned? could he have tuned? could we have tuned? could you have tuned? could they have tuned?
V-ing perfect
could I have been tuning? could you have been tuning? could he have been tuning? could we have been tuning? could you have been tuning? could they have been tuning?
Interro-negative form
Simple form
could I not tune? could you not tune? could he not tune? could we not tune? could you not tune? could they not tune?
V-ing form
could I not be tuning? could you not be tuning? could he not be tuning? could we not be tuning? could you not be tuning? could they not be tuning?
Perfect
could I not have tuned? could you not have tuned? could he not have tuned? could we not have tuned? could you not have tuned? could they not have tuned?
V-ing perfect
could I not have been tuning? could you not have been tuning? could he not have been tuning? could we not have been tuning? could you not have been tuning? could they not have been tuning?