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 couldn't tune you couldn't tune he couldn't tune we couldn't tune you couldn't tune they couldn't tune
V-ing form
I couldn't be tuning you couldn't be tuning he couldn't be tuning we couldn't be tuning you couldn't be tuning they couldn't be tuning
Perfect
I couldn't have tuned you couldn't have tuned he couldn't have tuned we couldn't have tuned you couldn't have tuned they couldn't have tuned
V-ing perfect
I couldn't have been tuning you couldn't have been tuning he couldn't have been tuning we couldn't have been tuning you couldn't have been tuning they couldn't 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
couldn't I tune? couldn't you tune? couldn't he tune? couldn't we tune? couldn't you tune? couldn't they tune?
V-ing form
couldn't I be tuning? couldn't you be tuning? couldn't he be tuning? couldn't we be tuning? couldn't you be tuning? couldn't they be tuning?
Perfect
couldn't I have tuned? couldn't you have tuned? couldn't he have tuned? couldn't we have tuned? couldn't you have tuned? couldn't they have tuned?
V-ing perfect
couldn't I have been tuning? couldn't you have been tuning? couldn't he have been tuning? couldn't we have been tuning? couldn't you have been tuning? couldn't they have been tuning?