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