English verb conjugation
MUST JACKKNIFE

Regular verb: jackknife - jackknifed - jackknifed

Affirmation

Simple form	V-ing form
I must jackknife you must jackknife he must jackknife we must jackknife you must jackknife they must jackknife	I must be jackknifing you must be jackknifing he must be jackknifing we must be jackknifing you must be jackknifing they must be jackknifing
Perfect	V-ing perfect
I must have jackknifed you must have jackknifed he must have jackknifed we must have jackknifed you must have jackknifed they must have jackknifed	I must have been jackknifing you must have been jackknifing he must have been jackknifing we must have been jackknifing you must have been jackknifing they must have been jackknifing

Negation

Simple form	V-ing form
I must not jackknife you must not jackknife he must not jackknife we must not jackknife you must not jackknife they must not jackknife	I must not be jackknifing you must not be jackknifing he must not be jackknifing we must not be jackknifing you must not be jackknifing they must not be jackknifing
Perfect	V-ing perfect
I must not have jackknifed you must not have jackknifed he must not have jackknifed we must not have jackknifed you must not have jackknifed they must not have jackknifed	I must not have been jackknifing you must not have been jackknifing he must not have been jackknifing we must not have been jackknifing you must not have been jackknifing they must not have been jackknifing

Interrogative form

Simple form	V-ing form
must I jackknife? must you jackknife? must he jackknife? must we jackknife? must you jackknife? must they jackknife?	must I be jackknifing? must you be jackknifing? must he be jackknifing? must we be jackknifing? must you be jackknifing? must they be jackknifing?
Perfect	V-ing perfect
must I have jackknifed? must you have jackknifed? must he have jackknifed? must we have jackknifed? must you have jackknifed? must they have jackknifed?	must I have been jackknifing? must you have been jackknifing? must he have been jackknifing? must we have been jackknifing? must you have been jackknifing? must they have been jackknifing?

Interro-negative form

Simple form	V-ing form
must I not jackknife? must you not jackknife? must he not jackknife? must we not jackknife? must you not jackknife? must they not jackknife?	must I not be jackknifing? must you not be jackknifing? must he not be jackknifing? must we not be jackknifing? must you not be jackknifing? must they not be jackknifing?
Perfect	V-ing perfect
must I not have jackknifed? must you not have jackknifed? must he not have jackknifed? must we not have jackknifed? must you not have jackknifed? must they not have jackknifed?	must I not have been jackknifing? must you not have been jackknifing? must he not have been jackknifing? must we not have been jackknifing? must you not have been jackknifing? must they not have been jackknifing?