should weaken
Regular verb: weaken - weakened- weakened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I should weaken
you should weaken
she should weaken
we should weaken
you should weaken
they should weaken 	I should be weakening
you should be weakening
she should be weakening
we should be weakening
you should be weakening
they should be weakening	I should have weakened
you should have weakened
she should have weakened
we should have weakened
you should have weakened
they should have weakened	I should have been weakening
you should have been weakening
she should have been weakening
we should have been weakening
you should have been weakening
they should have been weakening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I should not weaken
you should not weaken
she should not weaken
we should not weaken
you should not weaken
they should not weaken 	I should not be weakening
you should not be weakening
she should not be weakening
we should not be weakening
you should not be weakening
they should not be weakening	I should not have weakened
you should not have weakened
she should not have weakened
we should not have weakened
you should not have weakened
they should not have weakened	I should not have been weakening
you should not have been weakening
she should not have been weakening
we should not have been weakening
you should not have been weakening
they should not have been weakening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I weaken?
should you weaken?
should she weaken?
should we weaken?
should you weaken?
should they weaken? 	should I be weakening?
should you be weakening?
should she be weakening?
should we be weakening?
should you be weakening?
should they be weakening? 	should I have weakened?
should you have weakened?
should she have weakened?
should we have weakened?
should you have weakened?
should they have weakened? 	should I have been weakening?
should you have been weakening?
should she have been weakening?
should we have been weakening?
should you have been weakening?
should they have been weakening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I not weaken?
should you not weaken?
should she not weaken?
should we not weaken?
should you not weaken?
should they not weaken? 	should I not be weakening?
should you not be weakening?
should she not be weakening?
should we not be weakening?
should you not be weakening?
should they not be weakening? 	should I not have weakened?
should you not have weakened?
should she not have weakened?
should we not have weakened?
should you not have weakened?
should they not have weakened? 	should I not have been weakening?
should you not have been weakening?
should she not have been weakening?
should we not have been weakening?
should you not have been weakening?
should they not have been weakening?