could bitter
Regular verb: bitter - bittered- bittered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could bitter
you could bitter
he could bitter
we could bitter
you could bitter
they could bitter 	I could be bittering
you could be bittering
he could be bittering
we could be bittering
you could be bittering
they could be bittering	I could have bittered
you could have bittered
he could have bittered
we could have bittered
you could have bittered
they could have bittered	I could have been bittering
you could have been bittering
he could have been bittering
we could have been bittering
you could have been bittering
they could have been bittering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not bitter
you could not bitter
he could not bitter
we could not bitter
you could not bitter
they could not bitter 	I could not be bittering
you could not be bittering
he could not be bittering
we could not be bittering
you could not be bittering
they could not be bittering	I could not have bittered
you could not have bittered
he could not have bittered
we could not have bittered
you could not have bittered
they could not have bittered	I could not have been bittering
you could not have been bittering
he could not have been bittering
we could not have been bittering
you could not have been bittering
they could not have been bittering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I bitter?
could you bitter?
could he bitter?
could we bitter?
could you bitter?
could they bitter? 	could I be bittering?
could you be bittering?
could he be bittering?
could we be bittering?
could you be bittering?
could they be bittering? 	could I have bittered?
could you have bittered?
could he have bittered?
could we have bittered?
could you have bittered?
could they have bittered? 	could I have been bittering?
could you have been bittering?
could he have been bittering?
could we have been bittering?
could you have been bittering?
could they have been bittering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not bitter?
could you not bitter?
could he not bitter?
could we not bitter?
could you not bitter?
could they not bitter? 	could I not be bittering?
could you not be bittering?
could he not be bittering?
could we not be bittering?
could you not be bittering?
could they not be bittering? 	could I not have bittered?
could you not have bittered?
could he not have bittered?
could we not have bittered?
could you not have bittered?
could they not have bittered? 	could I not have been bittering?
could you not have been bittering?
could he not have been bittering?
could we not have been bittering?
could you not have been bittering?
could they not have been bittering?