should weaken
Regular verb: weaken - weakened- weakened

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