can tighten
Regular verb: tighten - tightened- tightened

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

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can't tighten
you can't tighten
he can't tighten
we can't tighten
you can't tighten
they can't tighten 	I can't be tightening
you can't be tightening
he can't be tightening
we can't be tightening
you can't be tightening
they can't be tightening	I can't have tightened
you can't have tightened
he can't have tightened
we can't have tightened
you can't have tightened
they can't have tightened	I can't have been tightening
you can't have been tightening
he can't have been tightening
we can't have been tightening
you can't have been tightening
they can't have been tightening	

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

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can't I tighten?
can't you tighten?
can't he tighten?
can't we tighten?
can't you tighten?
can't they tighten? 	can't I be tightening?
can't you be tightening?
can't he be tightening?
can't we be tightening?
can't you be tightening?
can't they be tightening? 	can't I have tightened?
can't you have tightened?
can't he have tightened?
can't we have tightened?
can't you have tightened?
can't they have tightened? 	can't I have been tightening?
can't you have been tightening?
can't he have been tightening?
can't we have been tightening?
can't you have been tightening?
can't they have been tightening?