should lengthen
Regular verb: lengthen - lengthened- lengthened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I should lengthen
you should lengthen
she should lengthen
we should lengthen
you should lengthen
they should lengthen 	I should be lengthening
you should be lengthening
she should be lengthening
we should be lengthening
you should be lengthening
they should be lengthening	I should have lengthened
you should have lengthened
she should have lengthened
we should have lengthened
you should have lengthened
they should have lengthened	I should have been lengthening
you should have been lengthening
she should have been lengthening
we should have been lengthening
you should have been lengthening
they should have been lengthening	

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

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I lengthen?
should you lengthen?
should she lengthen?
should we lengthen?
should you lengthen?
should they lengthen? 	should I be lengthening?
should you be lengthening?
should she be lengthening?
should we be lengthening?
should you be lengthening?
should they be lengthening? 	should I have lengthened?
should you have lengthened?
should she have lengthened?
should we have lengthened?
should you have lengthened?
should they have lengthened? 	should I have been lengthening?
should you have been lengthening?
should she have been lengthening?
should we have been lengthening?
should you have been lengthening?
should they have been lengthening? 	

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