I could clip you could clip he could clip we could clip you could clip they could clip
V-ing form
I could be clipping you could be clipping he could be clipping we could be clipping you could be clipping they could be clipping
Perfect
I could have clipped you could have clipped he could have clipped we could have clipped you could have clipped they could have clipped
V-ing perfect
I could have been clipping you could have been clipping he could have been clipping we could have been clipping you could have been clipping they could have been clipping
Negation
Simple form
I could not clip you could not clip he could not clip we could not clip you could not clip they could not clip
V-ing form
I could not be clipping you could not be clipping he could not be clipping we could not be clipping you could not be clipping they could not be clipping
Perfect
I could not have clipped you could not have clipped he could not have clipped we could not have clipped you could not have clipped they could not have clipped
V-ing perfect
I could not have been clipping you could not have been clipping he could not have been clipping we could not have been clipping you could not have been clipping they could not have been clipping
Interrogative form
Simple form
could I clip? could you clip? could he clip? could we clip? could you clip? could they clip?
V-ing form
could I be clipping? could you be clipping? could he be clipping? could we be clipping? could you be clipping? could they be clipping?
Perfect
could I have clipped? could you have clipped? could he have clipped? could we have clipped? could you have clipped? could they have clipped?
V-ing perfect
could I have been clipping? could you have been clipping? could he have been clipping? could we have been clipping? could you have been clipping? could they have been clipping?
Interro-negative form
Simple form
could I not clip? could you not clip? could he not clip? could we not clip? could you not clip? could they not clip?
V-ing form
could I not be clipping? could you not be clipping? could he not be clipping? could we not be clipping? could you not be clipping? could they not be clipping?
Perfect
could I not have clipped? could you not have clipped? could he not have clipped? could we not have clipped? could you not have clipped? could they not have clipped?
V-ing perfect
could I not have been clipping? could you not have been clipping? could he not have been clipping? could we not have been clipping? could you not have been clipping? could they not have been clipping?