I could dredge you could dredge he could dredge we could dredge you could dredge they could dredge
V-ing form
I could be dredging you could be dredging he could be dredging we could be dredging you could be dredging they could be dredging
Perfect
I could have dredged you could have dredged he could have dredged we could have dredged you could have dredged they could have dredged
V-ing perfect
I could have been dredging you could have been dredging he could have been dredging we could have been dredging you could have been dredging they could have been dredging
Negation
Simple form
I couldn't dredge you couldn't dredge he couldn't dredge we couldn't dredge you couldn't dredge they couldn't dredge
V-ing form
I couldn't be dredging you couldn't be dredging he couldn't be dredging we couldn't be dredging you couldn't be dredging they couldn't be dredging
Perfect
I couldn't have dredged you couldn't have dredged he couldn't have dredged we couldn't have dredged you couldn't have dredged they couldn't have dredged
V-ing perfect
I couldn't have been dredging you couldn't have been dredging he couldn't have been dredging we couldn't have been dredging you couldn't have been dredging they couldn't have been dredging
Interrogative form
Simple form
could I dredge? could you dredge? could he dredge? could we dredge? could you dredge? could they dredge?
V-ing form
could I be dredging? could you be dredging? could he be dredging? could we be dredging? could you be dredging? could they be dredging?
Perfect
could I have dredged? could you have dredged? could he have dredged? could we have dredged? could you have dredged? could they have dredged?
V-ing perfect
could I have been dredging? could you have been dredging? could he have been dredging? could we have been dredging? could you have been dredging? could they have been dredging?
Interro-negative form
Simple form
couldn't I dredge? couldn't you dredge? couldn't he dredge? couldn't we dredge? couldn't you dredge? couldn't they dredge?
V-ing form
couldn't I be dredging? couldn't you be dredging? couldn't he be dredging? couldn't we be dredging? couldn't you be dredging? couldn't they be dredging?
Perfect
couldn't I have dredged? couldn't you have dredged? couldn't he have dredged? couldn't we have dredged? couldn't you have dredged? couldn't they have dredged?
V-ing perfect
couldn't I have been dredging? couldn't you have been dredging? couldn't he have been dredging? couldn't we have been dredging? couldn't you have been dredging? couldn't they have been dredging?