English verb conjugation
COULD PREINVESTIGATE

Regular verb: preinvestigate - preinvestigated - preinvestigated

Affirmation

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

Negation

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

Interrogative form

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

Interro-negative form

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