must embitter
Regular verb: embitter - embittered- embittered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must embitter
you must embitter
she must embitter
we must embitter
you must embitter
they must embitter 	I must be embittering
you must be embittering
she must be embittering
we must be embittering
you must be embittering
they must be embittering	I must have embittered
you must have embittered
she must have embittered
we must have embittered
you must have embittered
they must have embittered	I must have been embittering
you must have been embittering
she must have been embittering
we must have been embittering
you must have been embittering
they must have been embittering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not embitter
you must not embitter
she must not embitter
we must not embitter
you must not embitter
they must not embitter 	I must not be embittering
you must not be embittering
she must not be embittering
we must not be embittering
you must not be embittering
they must not be embittering	I must not have embittered
you must not have embittered
she must not have embittered
we must not have embittered
you must not have embittered
they must not have embittered	I must not have been embittering
you must not have been embittering
she must not have been embittering
we must not have been embittering
you must not have been embittering
they must not have been embittering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I embitter?
must you embitter?
must she embitter?
must we embitter?
must you embitter?
must they embitter? 	must I be embittering?
must you be embittering?
must she be embittering?
must we be embittering?
must you be embittering?
must they be embittering? 	must I have embittered?
must you have embittered?
must she have embittered?
must we have embittered?
must you have embittered?
must they have embittered? 	must I have been embittering?
must you have been embittering?
must she have been embittering?
must we have been embittering?
must you have been embittering?
must they have been embittering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not embitter?
must you not embitter?
must she not embitter?
must we not embitter?
must you not embitter?
must they not embitter? 	must I not be embittering?
must you not be embittering?
must she not be embittering?
must we not be embittering?
must you not be embittering?
must they not be embittering? 	must I not have embittered?
must you not have embittered?
must she not have embittered?
must we not have embittered?
must you not have embittered?
must they not have embittered? 	must I not have been embittering?
must you not have been embittering?
must she not have been embittering?
must we not have been embittering?
must you not have been embittering?
must they not have been embittering?