could letter
Regular verb: letter - lettered- lettered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could letter
you could letter
he could letter
we could letter
you could letter
they could letter 	I could be lettering
you could be lettering
he could be lettering
we could be lettering
you could be lettering
they could be lettering	I could have lettered
you could have lettered
he could have lettered
we could have lettered
you could have lettered
they could have lettered	I could have been lettering
you could have been lettering
he could have been lettering
we could have been lettering
you could have been lettering
they could have been lettering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't letter
you couldn't letter
he couldn't letter
we couldn't letter
you couldn't letter
they couldn't letter 	I couldn't be lettering
you couldn't be lettering
he couldn't be lettering
we couldn't be lettering
you couldn't be lettering
they couldn't be lettering	I couldn't have lettered
you couldn't have lettered
he couldn't have lettered
we couldn't have lettered
you couldn't have lettered
they couldn't have lettered	I couldn't have been lettering
you couldn't have been lettering
he couldn't have been lettering
we couldn't have been lettering
you couldn't have been lettering
they couldn't have been lettering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I letter?
could you letter?
could he letter?
could we letter?
could you letter?
could they letter? 	could I be lettering?
could you be lettering?
could he be lettering?
could we be lettering?
could you be lettering?
could they be lettering? 	could I have lettered?
could you have lettered?
could he have lettered?
could we have lettered?
could you have lettered?
could they have lettered? 	could I have been lettering?
could you have been lettering?
could he have been lettering?
could we have been lettering?
could you have been lettering?
could they have been lettering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I letter?
couldn't you letter?
couldn't he letter?
couldn't we letter?
couldn't you letter?
couldn't they letter? 	couldn't I be lettering?
couldn't you be lettering?
couldn't he be lettering?
couldn't we be lettering?
couldn't you be lettering?
couldn't they be lettering? 	couldn't I have lettered?
couldn't you have lettered?
couldn't he have lettered?
couldn't we have lettered?
couldn't you have lettered?
couldn't they have lettered? 	couldn't I have been lettering?
couldn't you have been lettering?
couldn't he have been lettering?
couldn't we have been lettering?
couldn't you have been lettering?
couldn't they have been lettering?