English verb conjugation
MUST FASTEN

Regular verb: fasten - fastened - fastened

Affirmation

Simple form	V-ing form
I must fasten you must fasten she must fasten we must fasten you must fasten they must fasten	I must be fastening you must be fastening she must be fastening we must be fastening you must be fastening they must be fastening
Perfect	V-ing perfect
I must have fastened you must have fastened she must have fastened we must have fastened you must have fastened they must have fastened	I must have been fastening you must have been fastening she must have been fastening we must have been fastening you must have been fastening they must have been fastening

Negation

Simple form	V-ing form
I must not fasten you must not fasten she must not fasten we must not fasten you must not fasten they must not fasten	I must not be fastening you must not be fastening she must not be fastening we must not be fastening you must not be fastening they must not be fastening
Perfect	V-ing perfect
I must not have fastened you must not have fastened she must not have fastened we must not have fastened you must not have fastened they must not have fastened	I must not have been fastening you must not have been fastening she must not have been fastening we must not have been fastening you must not have been fastening they must not have been fastening

Interrogative form

Simple form	V-ing form
must I fasten? must you fasten? must she fasten? must we fasten? must you fasten? must they fasten?	must I be fastening? must you be fastening? must she be fastening? must we be fastening? must you be fastening? must they be fastening?
Perfect	V-ing perfect
must I have fastened? must you have fastened? must she have fastened? must we have fastened? must you have fastened? must they have fastened?	must I have been fastening? must you have been fastening? must she have been fastening? must we have been fastening? must you have been fastening? must they have been fastening?

Interro-negative form

Simple form	V-ing form
must I not fasten? must you not fasten? must she not fasten? must we not fasten? must you not fasten? must they not fasten?	must I not be fastening? must you not be fastening? must she not be fastening? must we not be fastening? must you not be fastening? must they not be fastening?
Perfect	V-ing perfect
must I not have fastened? must you not have fastened? must she not have fastened? must we not have fastened? must you not have fastened? must they not have fastened?	must I not have been fastening? must you not have been fastening? must she not have been fastening? must we not have been fastening? must you not have been fastening? must they not have been fastening?