I could plunge you could plunge she could plunge we could plunge you could plunge they could plunge
V-ing form
I could be plunging you could be plunging she could be plunging we could be plunging you could be plunging they could be plunging
Perfect
I could have plunged you could have plunged she could have plunged we could have plunged you could have plunged they could have plunged
V-ing perfect
I could have been plunging you could have been plunging she could have been plunging we could have been plunging you could have been plunging they could have been plunging
Negation
Simple form
I couldn't plunge you couldn't plunge she couldn't plunge we couldn't plunge you couldn't plunge they couldn't plunge
V-ing form
I couldn't be plunging you couldn't be plunging she couldn't be plunging we couldn't be plunging you couldn't be plunging they couldn't be plunging
Perfect
I couldn't have plunged you couldn't have plunged she couldn't have plunged we couldn't have plunged you couldn't have plunged they couldn't have plunged
V-ing perfect
I couldn't have been plunging you couldn't have been plunging she couldn't have been plunging we couldn't have been plunging you couldn't have been plunging they couldn't have been plunging
Interrogative form
Simple form
could I plunge? could you plunge? could she plunge? could we plunge? could you plunge? could they plunge?
V-ing form
could I be plunging? could you be plunging? could she be plunging? could we be plunging? could you be plunging? could they be plunging?
Perfect
could I have plunged? could you have plunged? could she have plunged? could we have plunged? could you have plunged? could they have plunged?
V-ing perfect
could I have been plunging? could you have been plunging? could she have been plunging? could we have been plunging? could you have been plunging? could they have been plunging?
Interro-negative form
Simple form
couldn't I plunge? couldn't you plunge? couldn't she plunge? couldn't we plunge? couldn't you plunge? couldn't they plunge?
V-ing form
couldn't I be plunging? couldn't you be plunging? couldn't she be plunging? couldn't we be plunging? couldn't you be plunging? couldn't they be plunging?
Perfect
couldn't I have plunged? couldn't you have plunged? couldn't she have plunged? couldn't we have plunged? couldn't you have plunged? couldn't they have plunged?
V-ing perfect
couldn't I have been plunging? couldn't you have been plunging? couldn't she have been plunging? couldn't we have been plunging? couldn't you have been plunging? couldn't they have been plunging?