must preinvestigate
Regular verb: preinvestigate - preinvestigated- preinvestigated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must preinvestigate
you must preinvestigate
he must preinvestigate
we must preinvestigate
you must preinvestigate
they must preinvestigate 	I must be preinvestigating
you must be preinvestigating
he must be preinvestigating
we must be preinvestigating
you must be preinvestigating
they must be preinvestigating	I must have preinvestigated
you must have preinvestigated
he must have preinvestigated
we must have preinvestigated
you must have preinvestigated
they must have preinvestigated	I must have been preinvestigating
you must have been preinvestigating
he must have been preinvestigating
we must have been preinvestigating
you must have been preinvestigating
they must have been preinvestigating	

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

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

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