English verb conjugation
CAN WITNESS

Regular verb: witness - witnessed - witnessed

Affirmation

Simple form	V-ing form
I can witness you can witness he can witness we can witness you can witness they can witness	I can be witnessing you can be witnessing he can be witnessing we can be witnessing you can be witnessing they can be witnessing
Perfect	V-ing perfect
I can have witnessed you can have witnessed he can have witnessed we can have witnessed you can have witnessed they can have witnessed	I can have been witnessing you can have been witnessing he can have been witnessing we can have been witnessing you can have been witnessing they can have been witnessing

Negation

Simple form	V-ing form
I can't witness you can't witness he can't witness we can't witness you can't witness they can't witness	I can't be witnessing you can't be witnessing he can't be witnessing we can't be witnessing you can't be witnessing they can't be witnessing
Perfect	V-ing perfect
I can't have witnessed you can't have witnessed he can't have witnessed we can't have witnessed you can't have witnessed they can't have witnessed	I can't have been witnessing you can't have been witnessing he can't have been witnessing we can't have been witnessing you can't have been witnessing they can't have been witnessing

Interrogative form

Simple form	V-ing form
can I witness? can you witness? can he witness? can we witness? can you witness? can they witness?	can I be witnessing? can you be witnessing? can he be witnessing? can we be witnessing? can you be witnessing? can they be witnessing?
Perfect	V-ing perfect
can I have witnessed? can you have witnessed? can he have witnessed? can we have witnessed? can you have witnessed? can they have witnessed?	can I have been witnessing? can you have been witnessing? can he have been witnessing? can we have been witnessing? can you have been witnessing? can they have been witnessing?

Interro-negative form

Simple form	V-ing form
can't I witness? can't you witness? can't he witness? can't we witness? can't you witness? can't they witness?	can't I be witnessing? can't you be witnessing? can't he be witnessing? can't we be witnessing? can't you be witnessing? can't they be witnessing?
Perfect	V-ing perfect
can't I have witnessed? can't you have witnessed? can't he have witnessed? can't we have witnessed? can't you have witnessed? can't they have witnessed?	can't I have been witnessing? can't you have been witnessing? can't he have been witnessing? can't we have been witnessing? can't you have been witnessing? can't they have been witnessing?