should back
Regular verb: back - backed- backed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I'd back
you'd back
she'd back
we'd back
you'd back
they'd back 	I'd be backing
you'd be backing
she'd be backing
we'd be backing
you'd be backing
they'd be backing	I should've backed
you should've backed
she should've backed
we should've backed
you should've backed
they should've backed	I should've been backing
you should've been backing
she should've been backing
we should've been backing
you should've been backing
they should've been backing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I shouldn't back
you shouldn't back
she shouldn't back
we shouldn't back
you shouldn't back
they shouldn't back 	I shouldn't be backing
you shouldn't be backing
she shouldn't be backing
we shouldn't be backing
you shouldn't be backing
they shouldn't be backing	I shouldn't have backed
you shouldn't have backed
she shouldn't have backed
we shouldn't have backed
you shouldn't have backed
they shouldn't have backed	I shouldn't have been backing
you shouldn't have been backing
she shouldn't have been backing
we shouldn't have been backing
you shouldn't have been backing
they shouldn't have been backing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I back?
should you back?
should she back?
should we back?
should you back?
should they back? 	should I be backing?
should you be backing?
should she be backing?
should we be backing?
should you be backing?
should they be backing? 	should I have backed?
should you have backed?
should she have backed?
should we have backed?
should you have backed?
should they have backed? 	should I have been backing?
should you have been backing?
should she have been backing?
should we have been backing?
should you have been backing?
should they have been backing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
shouldn't I back?
shouldn't you back?
shouldn't she back?
shouldn't we back?
shouldn't you back?
shouldn't they back? 	shouldn't I be backing?
shouldn't you be backing?
shouldn't she be backing?
shouldn't we be backing?
shouldn't you be backing?
shouldn't they be backing? 	shouldn't I have backed?
shouldn't you have backed?
shouldn't she have backed?
shouldn't we have backed?
shouldn't you have backed?
shouldn't they have backed? 	shouldn't I have been backing?
shouldn't you have been backing?
shouldn't she have been backing?
shouldn't we have been backing?
shouldn't you have been backing?
shouldn't they have been backing?