must decrease
Verbo regular: decrease - decreased- decreased

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must decrease
you must decrease
he must decrease
we must decrease
you must decrease
they must decrease 	I must be decreasing
you must be decreasing
he must be decreasing
we must be decreasing
you must be decreasing
they must be decreasing	I must have decreased
you must have decreased
he must have decreased
we must have decreased
you must have decreased
they must have decreased	I must have been decreasing
you must have been decreasing
he must have been decreasing
we must have been decreasing
you must have been decreasing
they must have been decreasing	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must not decrease
you must not decrease
he must not decrease
we must not decrease
you must not decrease
they must not decrease 	I must not be decreasing
you must not be decreasing
he must not be decreasing
we must not be decreasing
you must not be decreasing
they must not be decreasing	I must not have decreased
you must not have decreased
he must not have decreased
we must not have decreased
you must not have decreased
they must not have decreased	I must not have been decreasing
you must not have been decreasing
he must not have been decreasing
we must not have been decreasing
you must not have been decreasing
they must not have been decreasing	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I decrease?
must you decrease?
must he decrease?
must we decrease?
must you decrease?
must they decrease? 	must I be decreasing?
must you be decreasing?
must he be decreasing?
must we be decreasing?
must you be decreasing?
must they be decreasing? 	must I have decreased?
must you have decreased?
must he have decreased?
must we have decreased?
must you have decreased?
must they have decreased? 	must I have been decreasing?
must you have been decreasing?
must he have been decreasing?
must we have been decreasing?
must you have been decreasing?
must they have been decreasing? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I not decrease?
must you not decrease?
must he not decrease?
must we not decrease?
must you not decrease?
must they not decrease? 	must I not be decreasing?
must you not be decreasing?
must he not be decreasing?
must we not be decreasing?
must you not be decreasing?
must they not be decreasing? 	must I not have decreased?
must you not have decreased?
must he not have decreased?
must we not have decreased?
must you not have decreased?
must they not have decreased? 	must I not have been decreasing?
must you not have been decreasing?
must he not have been decreasing?
must we not have been decreasing?
must you not have been decreasing?
must they not have been decreasing?