could tune
Regular verb: tune - tuned- tuned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could tune
you could tune
he could tune
we could tune
you could tune
they could tune 	I could be tuning
you could be tuning
he could be tuning
we could be tuning
you could be tuning
they could be tuning	I could have tuned
you could have tuned
he could have tuned
we could have tuned
you could have tuned
they could have tuned	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 	V-ing form 	Perfect 	V-ing perfect 	
I could not tune
you could not tune
he could not tune
we could not tune
you could not tune
they could not tune 	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	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	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 	V-ing form 	Perfect 	V-ing perfect 	
could I tune?
could you tune?
could he tune?
could we tune?
could you tune?
could they tune? 	could I be tuning?
could you be tuning?
could he be tuning?
could we be tuning?
could you be tuning?
could they be tuning? 	could I have tuned?
could you have tuned?
could he have tuned?
could we have tuned?
could you have tuned?
could they have tuned? 	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 	V-ing form 	Perfect 	V-ing perfect 	
could I not tune?
could you not tune?
could he not tune?
could we not tune?
could you not tune?
could they not tune? 	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? 	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? 	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?