English verb conjugation
COULD UNDERUSE

Regular verb: underuse - underused - underused

Affirmation

Simple form	V-ing form
I could underuse you could underuse he could underuse we could underuse you could underuse they could underuse	I could be underusing you could be underusing he 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 he 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 he 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 he 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 he 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 he 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 he 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 he underuse? could we underuse? could you underuse? could they underuse?	could I be underusing? could you be underusing? could he 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 he 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 he 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 he 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 he 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 he 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 he have been underusing? couldn't we have been underusing? couldn't you have been underusing? couldn't they have been underusing?