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