I could submerge you could submerge she could submerge we could submerge you could submerge they could submerge
V-ing form
I could be submerging you could be submerging she could be submerging we could be submerging you could be submerging they could be submerging
Perfect
I could have submerged you could have submerged she could have submerged we could have submerged you could have submerged they could have submerged
V-ing perfect
I could have been submerging you could have been submerging she could have been submerging we could have been submerging you could have been submerging they could have been submerging
Negation
Simple form
I could not submerge you could not submerge she could not submerge we could not submerge you could not submerge they could not submerge
V-ing form
I could not be submerging you could not be submerging she could not be submerging we could not be submerging you could not be submerging they could not be submerging
Perfect
I could not have submerged you could not have submerged she could not have submerged we could not have submerged you could not have submerged they could not have submerged
V-ing perfect
I could not have been submerging you could not have been submerging she could not have been submerging we could not have been submerging you could not have been submerging they could not have been submerging
Interrogative form
Simple form
could I submerge? could you submerge? could she submerge? could we submerge? could you submerge? could they submerge?
V-ing form
could I be submerging? could you be submerging? could she be submerging? could we be submerging? could you be submerging? could they be submerging?
Perfect
could I have submerged? could you have submerged? could she have submerged? could we have submerged? could you have submerged? could they have submerged?
V-ing perfect
could I have been submerging? could you have been submerging? could she have been submerging? could we have been submerging? could you have been submerging? could they have been submerging?
Interro-negative form
Simple form
could I not submerge? could you not submerge? could she not submerge? could we not submerge? could you not submerge? could they not submerge?
V-ing form
could I not be submerging? could you not be submerging? could she not be submerging? could we not be submerging? could you not be submerging? could they not be submerging?
Perfect
could I not have submerged? could you not have submerged? could she not have submerged? could we not have submerged? could you not have submerged? could they not have submerged?
V-ing perfect
could I not have been submerging? could you not have been submerging? could she not have been submerging? could we not have been submerging? could you not have been submerging? could they not have been submerging?