should decrease
Regular verb: decrease - decreased- decreased

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I'd decrease
you'd decrease
she'd decrease
we'd decrease
you'd decrease
they'd decrease 	I'd be decreasing
you'd be decreasing
she'd be decreasing
we'd be decreasing
you'd be decreasing
they'd be decreasing	I should've decreased
you should've decreased
she should've decreased
we should've decreased
you should've decreased
they should've decreased	I should've been decreasing
you should've been decreasing
she should've been decreasing
we should've been decreasing
you should've been decreasing
they should've been decreasing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I shouldn't decrease
you shouldn't decrease
she shouldn't decrease
we shouldn't decrease
you shouldn't decrease
they shouldn't decrease 	I shouldn't be decreasing
you shouldn't be decreasing
she shouldn't be decreasing
we shouldn't be decreasing
you shouldn't be decreasing
they shouldn't be decreasing	I shouldn't have decreased
you shouldn't have decreased
she shouldn't have decreased
we shouldn't have decreased
you shouldn't have decreased
they shouldn't have decreased	I shouldn't have been decreasing
you shouldn't have been decreasing
she shouldn't have been decreasing
we shouldn't have been decreasing
you shouldn't have been decreasing
they shouldn't have been decreasing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I decrease?
should you decrease?
should she decrease?
should we decrease?
should you decrease?
should they decrease? 	should I be decreasing?
should you be decreasing?
should she be decreasing?
should we be decreasing?
should you be decreasing?
should they be decreasing? 	should I have decreased?
should you have decreased?
should she have decreased?
should we have decreased?
should you have decreased?
should they have decreased? 	should I have been decreasing?
should you have been decreasing?
should she have been decreasing?
should we have been decreasing?
should you have been decreasing?
should they have been decreasing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
shouldn't I decrease?
shouldn't you decrease?
shouldn't she decrease?
shouldn't we decrease?
shouldn't you decrease?
shouldn't they decrease? 	shouldn't I be decreasing?
shouldn't you be decreasing?
shouldn't she be decreasing?
shouldn't we be decreasing?
shouldn't you be decreasing?
shouldn't they be decreasing? 	shouldn't I have decreased?
shouldn't you have decreased?
shouldn't she have decreased?
shouldn't we have decreased?
shouldn't you have decreased?
shouldn't they have decreased? 	shouldn't I have been decreasing?
shouldn't you have been decreasing?
shouldn't she have been decreasing?
shouldn't we have been decreasing?
shouldn't you have been decreasing?
shouldn't they have been decreasing?