must invent
Regular verb: invent - invented- invented

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must invent
you must invent
he must invent
we must invent
you must invent
they must invent 	I must be inventing
you must be inventing
he must be inventing
we must be inventing
you must be inventing
they must be inventing	I must have invented
you must have invented
he must have invented
we must have invented
you must have invented
they must have invented	I must have been inventing
you must have been inventing
he must have been inventing
we must have been inventing
you must have been inventing
they must have been inventing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not invent
you must not invent
he must not invent
we must not invent
you must not invent
they must not invent 	I must not be inventing
you must not be inventing
he must not be inventing
we must not be inventing
you must not be inventing
they must not be inventing	I must not have invented
you must not have invented
he must not have invented
we must not have invented
you must not have invented
they must not have invented	I must not have been inventing
you must not have been inventing
he must not have been inventing
we must not have been inventing
you must not have been inventing
they must not have been inventing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I invent?
must you invent?
must he invent?
must we invent?
must you invent?
must they invent? 	must I be inventing?
must you be inventing?
must he be inventing?
must we be inventing?
must you be inventing?
must they be inventing? 	must I have invented?
must you have invented?
must he have invented?
must we have invented?
must you have invented?
must they have invented? 	must I have been inventing?
must you have been inventing?
must he have been inventing?
must we have been inventing?
must you have been inventing?
must they have been inventing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not invent?
must you not invent?
must he not invent?
must we not invent?
must you not invent?
must they not invent? 	must I not be inventing?
must you not be inventing?
must he not be inventing?
must we not be inventing?
must you not be inventing?
must they not be inventing? 	must I not have invented?
must you not have invented?
must he not have invented?
must we not have invented?
must you not have invented?
must they not have invented? 	must I not have been inventing?
must you not have been inventing?
must he not have been inventing?
must we not have been inventing?
must you not have been inventing?
must they not have been inventing?