should preinvestigate
Regular verb: preinvestigate - preinvestigated- preinvestigated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I'd preinvestigate
you'd preinvestigate
he'd preinvestigate
we'd preinvestigate
you'd preinvestigate
they'd preinvestigate 	I'd be preinvestigating
you'd be preinvestigating
he'd be preinvestigating
we'd be preinvestigating
you'd be preinvestigating
they'd be preinvestigating	I should've preinvestigated
you should've preinvestigated
he should've preinvestigated
we should've preinvestigated
you should've preinvestigated
they should've preinvestigated	I should've been preinvestigating
you should've been preinvestigating
he should've been preinvestigating
we should've been preinvestigating
you should've been preinvestigating
they should've been preinvestigating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I shouldn't preinvestigate
you shouldn't preinvestigate
he shouldn't preinvestigate
we shouldn't preinvestigate
you shouldn't preinvestigate
they shouldn't preinvestigate 	I shouldn't be preinvestigating
you shouldn't be preinvestigating
he shouldn't be preinvestigating
we shouldn't be preinvestigating
you shouldn't be preinvestigating
they shouldn't be preinvestigating	I shouldn't have preinvestigated
you shouldn't have preinvestigated
he shouldn't have preinvestigated
we shouldn't have preinvestigated
you shouldn't have preinvestigated
they shouldn't have preinvestigated	I shouldn't have been preinvestigating
you shouldn't have been preinvestigating
he shouldn't have been preinvestigating
we shouldn't have been preinvestigating
you shouldn't have been preinvestigating
they shouldn't have been preinvestigating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I preinvestigate?
should you preinvestigate?
should he preinvestigate?
should we preinvestigate?
should you preinvestigate?
should they preinvestigate? 	should I be preinvestigating?
should you be preinvestigating?
should he be preinvestigating?
should we be preinvestigating?
should you be preinvestigating?
should they be preinvestigating? 	should I have preinvestigated?
should you have preinvestigated?
should he have preinvestigated?
should we have preinvestigated?
should you have preinvestigated?
should they have preinvestigated? 	should I have been preinvestigating?
should you have been preinvestigating?
should he have been preinvestigating?
should we have been preinvestigating?
should you have been preinvestigating?
should they have been preinvestigating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
shouldn't I preinvestigate?
shouldn't you preinvestigate?
shouldn't he preinvestigate?
shouldn't we preinvestigate?
shouldn't you preinvestigate?
shouldn't they preinvestigate? 	shouldn't I be preinvestigating?
shouldn't you be preinvestigating?
shouldn't he be preinvestigating?
shouldn't we be preinvestigating?
shouldn't you be preinvestigating?
shouldn't they be preinvestigating? 	shouldn't I have preinvestigated?
shouldn't you have preinvestigated?
shouldn't he have preinvestigated?
shouldn't we have preinvestigated?
shouldn't you have preinvestigated?
shouldn't they have preinvestigated? 	shouldn't I have been preinvestigating?
shouldn't you have been preinvestigating?
shouldn't he have been preinvestigating?
shouldn't we have been preinvestigating?
shouldn't you have been preinvestigating?
shouldn't they have been preinvestigating?