English verb conjugation
COULD LETTER

Regular verb: letter - lettered - lettered

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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
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
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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?