must tighten
Regular verb: tighten - tightened- tightened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must tighten
you must tighten
she must tighten
we must tighten
you must tighten
they must tighten 	I must be tightening
you must be tightening
she must be tightening
we must be tightening
you must be tightening
they must be tightening	I must have tightened
you must have tightened
she must have tightened
we must have tightened
you must have tightened
they must have tightened	I must have been tightening
you must have been tightening
she must have been tightening
we must have been tightening
you must have been tightening
they must have been tightening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not tighten
you must not tighten
she must not tighten
we must not tighten
you must not tighten
they must not tighten 	I must not be tightening
you must not be tightening
she must not be tightening
we must not be tightening
you must not be tightening
they must not be tightening	I must not have tightened
you must not have tightened
she must not have tightened
we must not have tightened
you must not have tightened
they must not have tightened	I must not have been tightening
you must not have been tightening
she must not have been tightening
we must not have been tightening
you must not have been tightening
they must not have been tightening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I tighten?
must you tighten?
must she tighten?
must we tighten?
must you tighten?
must they tighten? 	must I be tightening?
must you be tightening?
must she be tightening?
must we be tightening?
must you be tightening?
must they be tightening? 	must I have tightened?
must you have tightened?
must she have tightened?
must we have tightened?
must you have tightened?
must they have tightened? 	must I have been tightening?
must you have been tightening?
must she have been tightening?
must we have been tightening?
must you have been tightening?
must they have been tightening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not tighten?
must you not tighten?
must she not tighten?
must we not tighten?
must you not tighten?
must they not tighten? 	must I not be tightening?
must you not be tightening?
must she not be tightening?
must we not be tightening?
must you not be tightening?
must they not be tightening? 	must I not have tightened?
must you not have tightened?
must she not have tightened?
must we not have tightened?
must you not have tightened?
must they not have tightened? 	must I not have been tightening?
must you not have been tightening?
must she not have been tightening?
must we not have been tightening?
must you not have been tightening?
must they not have been tightening?