English verb conjugation
COULD WITNESS

Regular verb: witness - witnessed - witnessed

Affirmation

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

Negation

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

Interrogative form

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

Interro-negative form

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