I could substantiate you could substantiate he could substantiate we could substantiate you could substantiate they could substantiate
V-ing form
I could be substantiating you could be substantiating he could be substantiating we could be substantiating you could be substantiating they could be substantiating
Perfect
I could have substantiated you could have substantiated he could have substantiated we could have substantiated you could have substantiated they could have substantiated
V-ing perfect
I could have been substantiating you could have been substantiating he could have been substantiating we could have been substantiating you could have been substantiating they could have been substantiating
Negation
Simple form
I could not substantiate you could not substantiate he could not substantiate we could not substantiate you could not substantiate they could not substantiate
V-ing form
I could not be substantiating you could not be substantiating he could not be substantiating we could not be substantiating you could not be substantiating they could not be substantiating
Perfect
I could not have substantiated you could not have substantiated he could not have substantiated we could not have substantiated you could not have substantiated they could not have substantiated
V-ing perfect
I could not have been substantiating you could not have been substantiating he could not have been substantiating we could not have been substantiating you could not have been substantiating they could not have been substantiating
Interrogative form
Simple form
could I substantiate? could you substantiate? could he substantiate? could we substantiate? could you substantiate? could they substantiate?
V-ing form
could I be substantiating? could you be substantiating? could he be substantiating? could we be substantiating? could you be substantiating? could they be substantiating?
Perfect
could I have substantiated? could you have substantiated? could he have substantiated? could we have substantiated? could you have substantiated? could they have substantiated?
V-ing perfect
could I have been substantiating? could you have been substantiating? could he have been substantiating? could we have been substantiating? could you have been substantiating? could they have been substantiating?
Interro-negative form
Simple form
could I not substantiate? could you not substantiate? could he not substantiate? could we not substantiate? could you not substantiate? could they not substantiate?
V-ing form
could I not be substantiating? could you not be substantiating? could he not be substantiating? could we not be substantiating? could you not be substantiating? could they not be substantiating?
Perfect
could I not have substantiated? could you not have substantiated? could he not have substantiated? could we not have substantiated? could you not have substantiated? could they not have substantiated?
V-ing perfect
could I not have been substantiating? could you not have been substantiating? could he not have been substantiating? could we not have been substantiating? could you not have been substantiating? could they not have been substantiating?