English verb conjugation
CAN LENGTHEN

Regular verb: lengthen - lengthened - lengthened

Affirmation

Simple form	V-ing form
I can lengthen you can lengthen she can lengthen we can lengthen you can lengthen they can lengthen	I can be lengthening you can be lengthening she 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 she 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 she 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 cannot lengthen you cannot lengthen she cannot lengthen we cannot lengthen you cannot lengthen they cannot lengthen	I cannot be lengthening you cannot be lengthening she cannot be lengthening we cannot be lengthening you cannot be lengthening they cannot be lengthening
Perfect	V-ing perfect
I cannot have lengthened you cannot have lengthened she cannot have lengthened we cannot have lengthened you cannot have lengthened they cannot have lengthened	I cannot have been lengthening you cannot have been lengthening she cannot have been lengthening we cannot have been lengthening you cannot have been lengthening they cannot have been lengthening

Interrogative form

Simple form	V-ing form
can I lengthen? can you lengthen? can she lengthen? can we lengthen? can you lengthen? can they lengthen?	can I be lengthening? can you be lengthening? can she 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 she 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 she 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 I not lengthen? can you not lengthen? can she not lengthen? can we not lengthen? can you not lengthen? can they not lengthen?	can I not be lengthening? can you not be lengthening? can she not be lengthening? can we not be lengthening? can you not be lengthening? can they not be lengthening?
Perfect	V-ing perfect
can I not have lengthened? can you not have lengthened? can she not have lengthened? can we not have lengthened? can you not have lengthened? can they not have lengthened?	can I not have been lengthening? can you not have been lengthening? can she not have been lengthening? can we not have been lengthening? can you not have been lengthening? can they not have been lengthening?