must tariff
Regular verb: tariff - tariffed- tariffed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must tariff
you must tariff
she must tariff
we must tariff
you must tariff
they must tariff 	I must be tariffing
you must be tariffing
she must be tariffing
we must be tariffing
you must be tariffing
they must be tariffing	I must have tariffed
you must have tariffed
she must have tariffed
we must have tariffed
you must have tariffed
they must have tariffed	I must have been tariffing
you must have been tariffing
she must have been tariffing
we must have been tariffing
you must have been tariffing
they must have been tariffing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't tariff
you mustn't tariff
she mustn't tariff
we mustn't tariff
you mustn't tariff
they mustn't tariff 	I mustn't be tariffing
you mustn't be tariffing
she mustn't be tariffing
we mustn't be tariffing
you mustn't be tariffing
they mustn't be tariffing	I mustn't have tariffed
you mustn't have tariffed
she mustn't have tariffed
we mustn't have tariffed
you mustn't have tariffed
they mustn't have tariffed	I mustn't have been tariffing
you mustn't have been tariffing
she mustn't have been tariffing
we mustn't have been tariffing
you mustn't have been tariffing
they mustn't have been tariffing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I tariff?
must you tariff?
must she tariff?
must we tariff?
must you tariff?
must they tariff? 	must I be tariffing?
must you be tariffing?
must she be tariffing?
must we be tariffing?
must you be tariffing?
must they be tariffing? 	must I have tariffed?
must you have tariffed?
must she have tariffed?
must we have tariffed?
must you have tariffed?
must they have tariffed? 	must I have been tariffing?
must you have been tariffing?
must she have been tariffing?
must we have been tariffing?
must you have been tariffing?
must they have been tariffing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I tariff?
mustn't you tariff?
mustn't she tariff?
mustn't we tariff?
mustn't you tariff?
mustn't they tariff? 	mustn't I be tariffing?
mustn't you be tariffing?
mustn't she be tariffing?
mustn't we be tariffing?
mustn't you be tariffing?
mustn't they be tariffing? 	mustn't I have tariffed?
mustn't you have tariffed?
mustn't she have tariffed?
mustn't we have tariffed?
mustn't you have tariffed?
mustn't they have tariffed? 	mustn't I have been tariffing?
mustn't you have been tariffing?
mustn't she have been tariffing?
mustn't we have been tariffing?
mustn't you have been tariffing?
mustn't they have been tariffing?