I could abstain you could abstain she could abstain we could abstain you could abstain they could abstain
V-ing form
I could be abstaining you could be abstaining she could be abstaining we could be abstaining you could be abstaining they could be abstaining
Perfect
I could have abstained you could have abstained she could have abstained we could have abstained you could have abstained they could have abstained
V-ing perfect
I could have been abstaining you could have been abstaining she could have been abstaining we could have been abstaining you could have been abstaining they could have been abstaining
Negation
Simple form
I could not abstain you could not abstain she could not abstain we could not abstain you could not abstain they could not abstain
V-ing form
I could not be abstaining you could not be abstaining she could not be abstaining we could not be abstaining you could not be abstaining they could not be abstaining
Perfect
I could not have abstained you could not have abstained she could not have abstained we could not have abstained you could not have abstained they could not have abstained
V-ing perfect
I could not have been abstaining you could not have been abstaining she could not have been abstaining we could not have been abstaining you could not have been abstaining they could not have been abstaining
Interrogative form
Simple form
could I abstain? could you abstain? could she abstain? could we abstain? could you abstain? could they abstain?
V-ing form
could I be abstaining? could you be abstaining? could she be abstaining? could we be abstaining? could you be abstaining? could they be abstaining?
Perfect
could I have abstained? could you have abstained? could she have abstained? could we have abstained? could you have abstained? could they have abstained?
V-ing perfect
could I have been abstaining? could you have been abstaining? could she have been abstaining? could we have been abstaining? could you have been abstaining? could they have been abstaining?
Interro-negative form
Simple form
could I not abstain? could you not abstain? could she not abstain? could we not abstain? could you not abstain? could they not abstain?
V-ing form
could I not be abstaining? could you not be abstaining? could she not be abstaining? could we not be abstaining? could you not be abstaining? could they not be abstaining?
Perfect
could I not have abstained? could you not have abstained? could she not have abstained? could we not have abstained? could you not have abstained? could they not have abstained?
V-ing perfect
could I not have been abstaining? could you not have been abstaining? could she not have been abstaining? could we not have been abstaining? could you not have been abstaining? could they not have been abstaining?