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 couldn't bitter
you couldn't bitter
he couldn't bitter
we couldn't bitter
you couldn't bitter
they couldn't bitter 	I couldn't be bittering
you couldn't be bittering
he couldn't be bittering
we couldn't be bittering
you couldn't be bittering
they couldn't be bittering	I couldn't have bittered
you couldn't have bittered
he couldn't have bittered
we couldn't have bittered
you couldn't have bittered
they couldn't have bittered	I couldn't have been bittering
you couldn't have been bittering
he couldn't have been bittering
we couldn't have been bittering
you couldn't have been bittering
they couldn't 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 	
couldn't I bitter?
couldn't you bitter?
couldn't he bitter?
couldn't we bitter?
couldn't you bitter?
couldn't they bitter? 	couldn't I be bittering?
couldn't you be bittering?
couldn't he be bittering?
couldn't we be bittering?
couldn't you be bittering?
couldn't they be bittering? 	couldn't I have bittered?
couldn't you have bittered?
couldn't he have bittered?
couldn't we have bittered?
couldn't you have bittered?
couldn't they have bittered? 	couldn't I have been bittering?
couldn't you have been bittering?
couldn't he have been bittering?
couldn't we have been bittering?
couldn't you have been bittering?
couldn't they have been bittering?