must quack
Verbo regular: quack - quacked- quacked

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I must quack
you must quack
he must quack
we must quack
you must quack
they must quack 	I must be quacking
you must be quacking
he must be quacking
we must be quacking
you must be quacking
they must be quacking	I must have quacked
you must have quacked
he must have quacked
we must have quacked
you must have quacked
they must have quacked	I must have been quacking
you must have been quacking
he must have been quacking
we must have been quacking
you must have been quacking
they must have been quacking	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I mustn't quack
you mustn't quack
he mustn't quack
we mustn't quack
you mustn't quack
they mustn't quack 	I mustn't be quacking
you mustn't be quacking
he mustn't be quacking
we mustn't be quacking
you mustn't be quacking
they mustn't be quacking	I mustn't have quacked
you mustn't have quacked
he mustn't have quacked
we mustn't have quacked
you mustn't have quacked
they mustn't have quacked	I mustn't have been quacking
you mustn't have been quacking
he mustn't have been quacking
we mustn't have been quacking
you mustn't have been quacking
they mustn't have been quacking	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
must I quack?
must you quack?
must he quack?
must we quack?
must you quack?
must they quack? 	must I be quacking?
must you be quacking?
must he be quacking?
must we be quacking?
must you be quacking?
must they be quacking? 	must I have quacked?
must you have quacked?
must he have quacked?
must we have quacked?
must you have quacked?
must they have quacked? 	must I have been quacking?
must you have been quacking?
must he have been quacking?
must we have been quacking?
must you have been quacking?
must they have been quacking? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
mustn't I quack?
mustn't you quack?
mustn't he quack?
mustn't we quack?
mustn't you quack?
mustn't they quack? 	mustn't I be quacking?
mustn't you be quacking?
mustn't he be quacking?
mustn't we be quacking?
mustn't you be quacking?
mustn't they be quacking? 	mustn't I have quacked?
mustn't you have quacked?
mustn't he have quacked?
mustn't we have quacked?
mustn't you have quacked?
mustn't they have quacked? 	mustn't I have been quacking?
mustn't you have been quacking?
mustn't he have been quacking?
mustn't we have been quacking?
mustn't you have been quacking?
mustn't they have been quacking?