must ski
Verbo regular: ski - skied- skied

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must ski
you must ski
she must ski
we must ski
you must ski
they must ski 	I must be skiing
you must be skiing
she must be skiing
we must be skiing
you must be skiing
they must be skiing	I must have skied
you must have skied
she 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
she must have been skiing
we must have been skiing
you must have been skiing
they must have been skiing	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I mustn't ski
you mustn't ski
she 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
she mustn't be skiing
we mustn't be skiing
you mustn't be skiing
they mustn't be skiing	I mustn't have skied
you mustn't have skied
she 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
she mustn't have been skiing
we mustn't have been skiing
you mustn't have been skiing
they mustn't have been skiing	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I ski?
must you ski?
must she ski?
must we ski?
must you ski?
must they ski? 	must I be skiing?
must you be skiing?
must she be skiing?
must we be skiing?
must you be skiing?
must they be skiing? 	must I have skied?
must you have skied?
must she 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 she have been skiing?
must we have been skiing?
must you have been skiing?
must they have been skiing? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
mustn't I ski?
mustn't you ski?
mustn't she 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 she be skiing?
mustn't we be skiing?
mustn't you be skiing?
mustn't they be skiing? 	mustn't I have skied?
mustn't you have skied?
mustn't she 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 she have been skiing?
mustn't we have been skiing?
mustn't you have been skiing?
mustn't they have been skiing?