must enquire
Regular verb: enquire - enquired- enquired

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must enquire
you must enquire
he must enquire
we must enquire
you must enquire
they must enquire 	I must be enquiring
you must be enquiring
he must be enquiring
we must be enquiring
you must be enquiring
they must be enquiring	I must have enquired
you must have enquired
he must have enquired
we must have enquired
you must have enquired
they must have enquired	I must have been enquiring
you must have been enquiring
he must have been enquiring
we must have been enquiring
you must have been enquiring
they must have been enquiring	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't enquire
you mustn't enquire
he mustn't enquire
we mustn't enquire
you mustn't enquire
they mustn't enquire 	I mustn't be enquiring
you mustn't be enquiring
he mustn't be enquiring
we mustn't be enquiring
you mustn't be enquiring
they mustn't be enquiring	I mustn't have enquired
you mustn't have enquired
he mustn't have enquired
we mustn't have enquired
you mustn't have enquired
they mustn't have enquired	I mustn't have been enquiring
you mustn't have been enquiring
he mustn't have been enquiring
we mustn't have been enquiring
you mustn't have been enquiring
they mustn't have been enquiring	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I enquire?
must you enquire?
must he enquire?
must we enquire?
must you enquire?
must they enquire? 	must I be enquiring?
must you be enquiring?
must he be enquiring?
must we be enquiring?
must you be enquiring?
must they be enquiring? 	must I have enquired?
must you have enquired?
must he have enquired?
must we have enquired?
must you have enquired?
must they have enquired? 	must I have been enquiring?
must you have been enquiring?
must he have been enquiring?
must we have been enquiring?
must you have been enquiring?
must they have been enquiring? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I enquire?
mustn't you enquire?
mustn't he enquire?
mustn't we enquire?
mustn't you enquire?
mustn't they enquire? 	mustn't I be enquiring?
mustn't you be enquiring?
mustn't he be enquiring?
mustn't we be enquiring?
mustn't you be enquiring?
mustn't they be enquiring? 	mustn't I have enquired?
mustn't you have enquired?
mustn't he have enquired?
mustn't we have enquired?
mustn't you have enquired?
mustn't they have enquired? 	mustn't I have been enquiring?
mustn't you have been enquiring?
mustn't he have been enquiring?
mustn't we have been enquiring?
mustn't you have been enquiring?
mustn't they have been enquiring?