English verb conjugation
MUST SKI

Regular verb: ski - skied - skied

Affirmation

Simple form	V-ing form
I must ski you must ski he must ski we must ski you must ski they must ski	I must be skiing you must be skiing he must be skiing we must be skiing you must be skiing they must be skiing
Perfect	V-ing perfect
I must have skied you must have skied he must have skied we must have skied you must have skied they must have skied	I must have been skiing you must have been skiing he must have been skiing we must have been skiing you must have been skiing they must have been skiing

Negation

Simple form	V-ing form
I mustn't ski you mustn't ski he mustn't ski we mustn't ski you mustn't ski they mustn't ski	I mustn't be skiing you mustn't be skiing he mustn't be skiing we mustn't be skiing you mustn't be skiing they mustn't be skiing
Perfect	V-ing perfect
I mustn't have skied you mustn't have skied he mustn't have skied we mustn't have skied you mustn't have skied they mustn't have skied	I mustn't have been skiing you mustn't have been skiing he mustn't have been skiing we mustn't have been skiing you mustn't have been skiing they mustn't have been skiing

Interrogative form

Simple form	V-ing form
must I ski? must you ski? must he ski? must we ski? must you ski? must they ski?	must I be skiing? must you be skiing? must he be skiing? must we be skiing? must you be skiing? must they be skiing?
Perfect	V-ing perfect
must I have skied? must you have skied? must he have skied? must we have skied? must you have skied? must they have skied?	must I have been skiing? must you have been skiing? must he have been skiing? must we have been skiing? must you have been skiing? must they have been skiing?

Interro-negative form

Simple form	V-ing form
mustn't I ski? mustn't you ski? mustn't he ski? mustn't we ski? mustn't you ski? mustn't they ski?	mustn't I be skiing? mustn't you be skiing? mustn't he be skiing? mustn't we be skiing? mustn't you be skiing? mustn't they be skiing?
Perfect	V-ing perfect
mustn't I have skied? mustn't you have skied? mustn't he have skied? mustn't we have skied? mustn't you have skied? mustn't they have skied?	mustn't I have been skiing? mustn't you have been skiing? mustn't he have been skiing? mustn't we have been skiing? mustn't you have been skiing? mustn't they have been skiing?