must fathom
Regular verb: fathom - fathomed- fathomed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must fathom
you must fathom
she must fathom
we must fathom
you must fathom
they must fathom 	I must be fathoming
you must be fathoming
she must be fathoming
we must be fathoming
you must be fathoming
they must be fathoming	I must have fathomed
you must have fathomed
she must have fathomed
we must have fathomed
you must have fathomed
they must have fathomed	I must have been fathoming
you must have been fathoming
she must have been fathoming
we must have been fathoming
you must have been fathoming
they must have been fathoming	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not fathom
you must not fathom
she must not fathom
we must not fathom
you must not fathom
they must not fathom 	I must not be fathoming
you must not be fathoming
she must not be fathoming
we must not be fathoming
you must not be fathoming
they must not be fathoming	I must not have fathomed
you must not have fathomed
she must not have fathomed
we must not have fathomed
you must not have fathomed
they must not have fathomed	I must not have been fathoming
you must not have been fathoming
she must not have been fathoming
we must not have been fathoming
you must not have been fathoming
they must not have been fathoming	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I fathom?
must you fathom?
must she fathom?
must we fathom?
must you fathom?
must they fathom? 	must I be fathoming?
must you be fathoming?
must she be fathoming?
must we be fathoming?
must you be fathoming?
must they be fathoming? 	must I have fathomed?
must you have fathomed?
must she have fathomed?
must we have fathomed?
must you have fathomed?
must they have fathomed? 	must I have been fathoming?
must you have been fathoming?
must she have been fathoming?
must we have been fathoming?
must you have been fathoming?
must they have been fathoming? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not fathom?
must you not fathom?
must she not fathom?
must we not fathom?
must you not fathom?
must they not fathom? 	must I not be fathoming?
must you not be fathoming?
must she not be fathoming?
must we not be fathoming?
must you not be fathoming?
must they not be fathoming? 	must I not have fathomed?
must you not have fathomed?
must she not have fathomed?
must we not have fathomed?
must you not have fathomed?
must they not have fathomed? 	must I not have been fathoming?
must you not have been fathoming?
must she not have been fathoming?
must we not have been fathoming?
must you not have been fathoming?
must they not have been fathoming?