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 mustn't jackknife you mustn't jackknife he mustn't jackknife we mustn't jackknife you mustn't jackknife they mustn't jackknife	I mustn't be jackknifing you mustn't be jackknifing he mustn't be jackknifing we mustn't be jackknifing you mustn't be jackknifing they mustn't be jackknifing
Perfect	V-ing perfect
I mustn't have jackknifed you mustn't have jackknifed he mustn't have jackknifed we mustn't have jackknifed you mustn't have jackknifed they mustn't have jackknifed	I mustn't have been jackknifing you mustn't have been jackknifing he mustn't have been jackknifing we mustn't have been jackknifing you mustn't have been jackknifing they mustn't 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
mustn't I jackknife? mustn't you jackknife? mustn't he jackknife? mustn't we jackknife? mustn't you jackknife? mustn't they jackknife?	mustn't I be jackknifing? mustn't you be jackknifing? mustn't he be jackknifing? mustn't we be jackknifing? mustn't you be jackknifing? mustn't they be jackknifing?
Perfect	V-ing perfect
mustn't I have jackknifed? mustn't you have jackknifed? mustn't he have jackknifed? mustn't we have jackknifed? mustn't you have jackknifed? mustn't they have jackknifed?	mustn't I have been jackknifing? mustn't you have been jackknifing? mustn't he have been jackknifing? mustn't we have been jackknifing? mustn't you have been jackknifing? mustn't they have been jackknifing?