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