must water-ski
Regular verb: water-ski - water-skied- water-skied

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

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

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

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