English verb conjugation
COULD UNDERUSE

Regular verb: underuse - underused - underused

Affirmation

Simple form	V-ing form
I could underuse you could underuse she could underuse we could underuse you could underuse they could underuse	I could be underusing you could be underusing she could be underusing we could be underusing you could be underusing they could be underusing
Perfect	V-ing perfect
I could have underused you could have underused she could have underused we could have underused you could have underused they could have underused	I could have been underusing you could have been underusing she could have been underusing we could have been underusing you could have been underusing they could have been underusing

Negation

Simple form	V-ing form
I couldn't underuse you couldn't underuse she couldn't underuse we couldn't underuse you couldn't underuse they couldn't underuse	I couldn't be underusing you couldn't be underusing she couldn't be underusing we couldn't be underusing you couldn't be underusing they couldn't be underusing
Perfect	V-ing perfect
I couldn't have underused you couldn't have underused she couldn't have underused we couldn't have underused you couldn't have underused they couldn't have underused	I couldn't have been underusing you couldn't have been underusing she couldn't have been underusing we couldn't have been underusing you couldn't have been underusing they couldn't have been underusing

Interrogative form

Simple form	V-ing form
could I underuse? could you underuse? could she underuse? could we underuse? could you underuse? could they underuse?	could I be underusing? could you be underusing? could she be underusing? could we be underusing? could you be underusing? could they be underusing?
Perfect	V-ing perfect
could I have underused? could you have underused? could she have underused? could we have underused? could you have underused? could they have underused?	could I have been underusing? could you have been underusing? could she have been underusing? could we have been underusing? could you have been underusing? could they have been underusing?

Interro-negative form

Simple form	V-ing form
couldn't I underuse? couldn't you underuse? couldn't she underuse? couldn't we underuse? couldn't you underuse? couldn't they underuse?	couldn't I be underusing? couldn't you be underusing? couldn't she be underusing? couldn't we be underusing? couldn't you be underusing? couldn't they be underusing?
Perfect	V-ing perfect
couldn't I have underused? couldn't you have underused? couldn't she have underused? couldn't we have underused? couldn't you have underused? couldn't they have underused?	couldn't I have been underusing? couldn't you have been underusing? couldn't she have been underusing? couldn't we have been underusing? couldn't you have been underusing? couldn't they have been underusing?