must rub
Regular verb: rub - rubbed- rubbed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must rub
you must rub
she must rub
we must rub
you must rub
they must rub 	I must be rubbing
you must be rubbing
she must be rubbing
we must be rubbing
you must be rubbing
they must be rubbing	I must have rubbed
you must have rubbed
she must have rubbed
we must have rubbed
you must have rubbed
they must have rubbed	I must have been rubbing
you must have been rubbing
she must have been rubbing
we must have been rubbing
you must have been rubbing
they must have been rubbing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not rub
you must not rub
she must not rub
we must not rub
you must not rub
they must not rub 	I must not be rubbing
you must not be rubbing
she must not be rubbing
we must not be rubbing
you must not be rubbing
they must not be rubbing	I must not have rubbed
you must not have rubbed
she must not have rubbed
we must not have rubbed
you must not have rubbed
they must not have rubbed	I must not have been rubbing
you must not have been rubbing
she must not have been rubbing
we must not have been rubbing
you must not have been rubbing
they must not have been rubbing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I rub?
must you rub?
must she rub?
must we rub?
must you rub?
must they rub? 	must I be rubbing?
must you be rubbing?
must she be rubbing?
must we be rubbing?
must you be rubbing?
must they be rubbing? 	must I have rubbed?
must you have rubbed?
must she have rubbed?
must we have rubbed?
must you have rubbed?
must they have rubbed? 	must I have been rubbing?
must you have been rubbing?
must she have been rubbing?
must we have been rubbing?
must you have been rubbing?
must they have been rubbing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not rub?
must you not rub?
must she not rub?
must we not rub?
must you not rub?
must they not rub? 	must I not be rubbing?
must you not be rubbing?
must she not be rubbing?
must we not be rubbing?
must you not be rubbing?
must they not be rubbing? 	must I not have rubbed?
must you not have rubbed?
must she not have rubbed?
must we not have rubbed?
must you not have rubbed?
must they not have rubbed? 	must I not have been rubbing?
must you not have been rubbing?
must she not have been rubbing?
must we not have been rubbing?
must you not have been rubbing?
must they not have been rubbing?