English verb conjugation
CAN TIGHTEN

Regular verb: tighten - tightened - tightened

Affirmation

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