must retrofit
Irregular verb: retrofit - retrofit- retrofit

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must retrofit
you must retrofit
he must retrofit
we must retrofit
you must retrofit
they must retrofit 	I must be retrofiting
you must be retrofiting
he must be retrofiting
we must be retrofiting
you must be retrofiting
they must be retrofiting	I must have retrofit
you must have retrofit
he must have retrofit
we must have retrofit
you must have retrofit
they must have retrofit	I must have been retrofiting
you must have been retrofiting
he must have been retrofiting
we must have been retrofiting
you must have been retrofiting
they must have been retrofiting	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not retrofit
you must not retrofit
he must not retrofit
we must not retrofit
you must not retrofit
they must not retrofit 	I must not be retrofiting
you must not be retrofiting
he must not be retrofiting
we must not be retrofiting
you must not be retrofiting
they must not be retrofiting	I must not have retrofit
you must not have retrofit
he must not have retrofit
we must not have retrofit
you must not have retrofit
they must not have retrofit	I must not have been retrofiting
you must not have been retrofiting
he must not have been retrofiting
we must not have been retrofiting
you must not have been retrofiting
they must not have been retrofiting	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I retrofit?
must you retrofit?
must he retrofit?
must we retrofit?
must you retrofit?
must they retrofit? 	must I be retrofiting?
must you be retrofiting?
must he be retrofiting?
must we be retrofiting?
must you be retrofiting?
must they be retrofiting? 	must I have retrofit?
must you have retrofit?
must he have retrofit?
must we have retrofit?
must you have retrofit?
must they have retrofit? 	must I have been retrofiting?
must you have been retrofiting?
must he have been retrofiting?
must we have been retrofiting?
must you have been retrofiting?
must they have been retrofiting? 	

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