English verb conjugation
CAN LETTER

Regular verb: letter - lettered - lettered

Affirmation

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

Negation

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

Interrogative form

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

Interro-negative form

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