must lesson
Regular verb: lesson - lessoned- lessoned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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	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	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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	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	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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? 	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? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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? 	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?