must witness
Regular verb: witness - witnessed- witnessed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must witness
you must witness
she must witness
we must witness
you must witness
they must witness 	I must be witnessing
you must be witnessing
she must be witnessing
we must be witnessing
you must be witnessing
they must be witnessing	I must have witnessed
you must have witnessed
she must have witnessed
we must have witnessed
you must have witnessed
they must have witnessed	I must have been witnessing
you must have been witnessing
she must have been witnessing
we must have been witnessing
you must have been witnessing
they must have been witnessing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't witness
you mustn't witness
she mustn't witness
we mustn't witness
you mustn't witness
they mustn't witness 	I mustn't be witnessing
you mustn't be witnessing
she mustn't be witnessing
we mustn't be witnessing
you mustn't be witnessing
they mustn't be witnessing	I mustn't have witnessed
you mustn't have witnessed
she mustn't have witnessed
we mustn't have witnessed
you mustn't have witnessed
they mustn't have witnessed	I mustn't have been witnessing
you mustn't have been witnessing
she mustn't have been witnessing
we mustn't have been witnessing
you mustn't have been witnessing
they mustn't have been witnessing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I witness?
must you witness?
must she witness?
must we witness?
must you witness?
must they witness? 	must I be witnessing?
must you be witnessing?
must she be witnessing?
must we be witnessing?
must you be witnessing?
must they be witnessing? 	must I have witnessed?
must you have witnessed?
must she have witnessed?
must we have witnessed?
must you have witnessed?
must they have witnessed? 	must I have been witnessing?
must you have been witnessing?
must she have been witnessing?
must we have been witnessing?
must you have been witnessing?
must they have been witnessing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I witness?
mustn't you witness?
mustn't she witness?
mustn't we witness?
mustn't you witness?
mustn't they witness? 	mustn't I be witnessing?
mustn't you be witnessing?
mustn't she be witnessing?
mustn't we be witnessing?
mustn't you be witnessing?
mustn't they be witnessing? 	mustn't I have witnessed?
mustn't you have witnessed?
mustn't she have witnessed?
mustn't we have witnessed?
mustn't you have witnessed?
mustn't they have witnessed? 	mustn't I have been witnessing?
mustn't you have been witnessing?
mustn't she have been witnessing?
mustn't we have been witnessing?
mustn't you have been witnessing?
mustn't they have been witnessing?