I could lesson you could lesson he could lesson we could lesson you could lesson they could lesson
V-ing form
I could be lessoning you could be lessoning he could be lessoning we could be lessoning you could be lessoning they could be lessoning
Perfect
I could have lessoned you could have lessoned he could have lessoned we could have lessoned you could have lessoned they could have lessoned
V-ing perfect
I could have been lessoning you could have been lessoning he could have been lessoning we could have been lessoning you could have been lessoning they could have been lessoning
Negation
Simple form
I could not lesson you could not lesson he could not lesson we could not lesson you could not lesson they could not lesson
V-ing form
I could not be lessoning you could not be lessoning he could not be lessoning we could not be lessoning you could not be lessoning they could not be lessoning
Perfect
I could not have lessoned you could not have lessoned he could not have lessoned we could not have lessoned you could not have lessoned they could not have lessoned
V-ing perfect
I could not have been lessoning you could not have been lessoning he could not have been lessoning we could not have been lessoning you could not have been lessoning they could not have been lessoning
Interrogative form
Simple form
could I lesson? could you lesson? could he lesson? could we lesson? could you lesson? could they lesson?
V-ing form
could I be lessoning? could you be lessoning? could he be lessoning? could we be lessoning? could you be lessoning? could they be lessoning?
Perfect
could I have lessoned? could you have lessoned? could he have lessoned? could we have lessoned? could you have lessoned? could they have lessoned?
V-ing perfect
could I have been lessoning? could you have been lessoning? could he have been lessoning? could we have been lessoning? could you have been lessoning? could they have been lessoning?
Interro-negative form
Simple form
could I not lesson? could you not lesson? could he not lesson? could we not lesson? could you not lesson? could they not lesson?
V-ing form
could I not be lessoning? could you not be lessoning? could he not be lessoning? could we not be lessoning? could you not be lessoning? could they not be lessoning?
Perfect
could I not have lessoned? could you not have lessoned? could he not have lessoned? could we not have lessoned? could you not have lessoned? could they not have lessoned?
V-ing perfect
could I not have been lessoning? could you not have been lessoning? could he not have been lessoning? could we not have been lessoning? could you not have been lessoning? could they not have been lessoning?