
Regular verb: lesson - lessoned - lessoned
Simple form | V-ing form | 
| I must lesson you must lesson she must lesson we must lesson you must lesson they must lesson  | I must be lessoning you must be lessoning she must be lessoning we must be lessoning you must be lessoning they must be lessoning  | 
Perfect | V-ing perfect | 
| I must have lessoned you must have lessoned she must have lessoned we must have lessoned you must have lessoned they must have lessoned  | I must have been lessoning you must have been lessoning she must have been lessoning we must have been lessoning you must have been lessoning they must have been lessoning  | 
Simple form | V-ing form | 
| I mustn't lesson you mustn't lesson she mustn't lesson we mustn't lesson you mustn't lesson they mustn't lesson  | I mustn't be lessoning you mustn't be lessoning she mustn't be lessoning we mustn't be lessoning you mustn't be lessoning they mustn't be lessoning  | 
Perfect | V-ing perfect | 
| I mustn't have lessoned you mustn't have lessoned she mustn't have lessoned we mustn't have lessoned you mustn't have lessoned they mustn't have lessoned  | I mustn't have been lessoning you mustn't have been lessoning she mustn't have been lessoning we mustn't have been lessoning you mustn't have been lessoning they mustn't have been lessoning  | 
Simple form | V-ing form | 
| must I lesson? must you lesson? must she lesson? must we lesson? must you lesson? must they lesson?  | must I be lessoning? must you be lessoning? must she be lessoning? must we be lessoning? must you be lessoning? must they be lessoning?  | 
Perfect | V-ing perfect | 
| must I have lessoned? must you have lessoned? must she have lessoned? must we have lessoned? must you have lessoned? must they have lessoned?  | must I have been lessoning? must you have been lessoning? must she have been lessoning? must we have been lessoning? must you have been lessoning? must they have been lessoning?  | 
Simple form | V-ing form | 
| mustn't I lesson? mustn't you lesson? mustn't she lesson? mustn't we lesson? mustn't you lesson? mustn't they lesson?  | mustn't I be lessoning? mustn't you be lessoning? mustn't she be lessoning? mustn't we be lessoning? mustn't you be lessoning? mustn't they be lessoning?  | 
Perfect | V-ing perfect | 
| mustn't I have lessoned? mustn't you have lessoned? mustn't she have lessoned? mustn't we have lessoned? mustn't you have lessoned? mustn't they have lessoned?  | mustn't I have been lessoning? mustn't you have been lessoning? mustn't she have been lessoning? mustn't we have been lessoning? mustn't you have been lessoning? mustn't they have been lessoning?  |