English verb conjugation
COULD BACK

Regular verb: back - backed - backed

Affirmation

Simple form	V-ing form
I could back you could back he could back we could back you could back they could back	I could be backing you could be backing he could be backing we could be backing you could be backing they could be backing
Perfect	V-ing perfect
I could have backed you could have backed he could have backed we could have backed you could have backed they could have backed	I could have been backing you could have been backing he could have been backing we could have been backing you could have been backing they could have been backing

Negation

Simple form	V-ing form
I couldn't back you couldn't back he couldn't back we couldn't back you couldn't back they couldn't back	I couldn't be backing you couldn't be backing he couldn't be backing we couldn't be backing you couldn't be backing they couldn't be backing
Perfect	V-ing perfect
I couldn't have backed you couldn't have backed he couldn't have backed we couldn't have backed you couldn't have backed they couldn't have backed	I couldn't have been backing you couldn't have been backing he couldn't have been backing we couldn't have been backing you couldn't have been backing they couldn't have been backing

Interrogative form

Simple form	V-ing form
could I back? could you back? could he back? could we back? could you back? could they back?	could I be backing? could you be backing? could he be backing? could we be backing? could you be backing? could they be backing?
Perfect	V-ing perfect
could I have backed? could you have backed? could he have backed? could we have backed? could you have backed? could they have backed?	could I have been backing? could you have been backing? could he have been backing? could we have been backing? could you have been backing? could they have been backing?

Interro-negative form

Simple form	V-ing form
couldn't I back? couldn't you back? couldn't he back? couldn't we back? couldn't you back? couldn't they back?	couldn't I be backing? couldn't you be backing? couldn't he be backing? couldn't we be backing? couldn't you be backing? couldn't they be backing?
Perfect	V-ing perfect
couldn't I have backed? couldn't you have backed? couldn't he have backed? couldn't we have backed? couldn't you have backed? couldn't they have backed?	couldn't I have been backing? couldn't you have been backing? couldn't he have been backing? couldn't we have been backing? couldn't you have been backing? couldn't they have been backing?