must descale
Verbo regular: descale - descaled- descaled

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I must descale
you must descale
she must descale
we must descale
you must descale
they must descale 	I must be descaling
you must be descaling
she must be descaling
we must be descaling
you must be descaling
they must be descaling	I must have descaled
you must have descaled
she must have descaled
we must have descaled
you must have descaled
they must have descaled	I must have been descaling
you must have been descaling
she must have been descaling
we must have been descaling
you must have been descaling
they must have been descaling	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I mustn't descale
you mustn't descale
she mustn't descale
we mustn't descale
you mustn't descale
they mustn't descale 	I mustn't be descaling
you mustn't be descaling
she mustn't be descaling
we mustn't be descaling
you mustn't be descaling
they mustn't be descaling	I mustn't have descaled
you mustn't have descaled
she mustn't have descaled
we mustn't have descaled
you mustn't have descaled
they mustn't have descaled	I mustn't have been descaling
you mustn't have been descaling
she mustn't have been descaling
we mustn't have been descaling
you mustn't have been descaling
they mustn't have been descaling	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
must I descale?
must you descale?
must she descale?
must we descale?
must you descale?
must they descale? 	must I be descaling?
must you be descaling?
must she be descaling?
must we be descaling?
must you be descaling?
must they be descaling? 	must I have descaled?
must you have descaled?
must she have descaled?
must we have descaled?
must you have descaled?
must they have descaled? 	must I have been descaling?
must you have been descaling?
must she have been descaling?
must we have been descaling?
must you have been descaling?
must they have been descaling? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
mustn't I descale?
mustn't you descale?
mustn't she descale?
mustn't we descale?
mustn't you descale?
mustn't they descale? 	mustn't I be descaling?
mustn't you be descaling?
mustn't she be descaling?
mustn't we be descaling?
mustn't you be descaling?
mustn't they be descaling? 	mustn't I have descaled?
mustn't you have descaled?
mustn't she have descaled?
mustn't we have descaled?
mustn't you have descaled?
mustn't they have descaled? 	mustn't I have been descaling?
mustn't you have been descaling?
mustn't she have been descaling?
mustn't we have been descaling?
mustn't you have been descaling?
mustn't they have been descaling?