English verb conjugation
CAN LENGTHEN

Regular verb: lengthen - lengthened - lengthened

Affirmation

Simple form	V-ing form
I can lengthen you can lengthen he can lengthen we can lengthen you can lengthen they can lengthen	I can be lengthening you can be lengthening he can be lengthening we can be lengthening you can be lengthening they can be lengthening
Perfect	V-ing perfect
I can have lengthened you can have lengthened he can have lengthened we can have lengthened you can have lengthened they can have lengthened	I can have been lengthening you can have been lengthening he can have been lengthening we can have been lengthening you can have been lengthening they can have been lengthening

Negation

Simple form	V-ing form
I can't lengthen you can't lengthen he can't lengthen we can't lengthen you can't lengthen they can't lengthen	I can't be lengthening you can't be lengthening he can't be lengthening we can't be lengthening you can't be lengthening they can't be lengthening
Perfect	V-ing perfect
I can't have lengthened you can't have lengthened he can't have lengthened we can't have lengthened you can't have lengthened they can't have lengthened	I can't have been lengthening you can't have been lengthening he can't have been lengthening we can't have been lengthening you can't have been lengthening they can't have been lengthening

Interrogative form

Simple form	V-ing form
can I lengthen? can you lengthen? can he lengthen? can we lengthen? can you lengthen? can they lengthen?	can I be lengthening? can you be lengthening? can he be lengthening? can we be lengthening? can you be lengthening? can they be lengthening?
Perfect	V-ing perfect
can I have lengthened? can you have lengthened? can he have lengthened? can we have lengthened? can you have lengthened? can they have lengthened?	can I have been lengthening? can you have been lengthening? can he have been lengthening? can we have been lengthening? can you have been lengthening? can they have been lengthening?

Interro-negative form

Simple form	V-ing form
can't I lengthen? can't you lengthen? can't he lengthen? can't we lengthen? can't you lengthen? can't they lengthen?	can't I be lengthening? can't you be lengthening? can't he be lengthening? can't we be lengthening? can't you be lengthening? can't they be lengthening?
Perfect	V-ing perfect
can't I have lengthened? can't you have lengthened? can't he have lengthened? can't we have lengthened? can't you have lengthened? can't they have lengthened?	can't I have been lengthening? can't you have been lengthening? can't he have been lengthening? can't we have been lengthening? can't you have been lengthening? can't they have been lengthening?