I could engineer you could engineer he could engineer we could engineer you could engineer they could engineer
V-ing form
I could be engineering you could be engineering he could be engineering we could be engineering you could be engineering they could be engineering
Perfect
I could have engineered you could have engineered he could have engineered we could have engineered you could have engineered they could have engineered
V-ing perfect
I could have been engineering you could have been engineering he could have been engineering we could have been engineering you could have been engineering they could have been engineering
Negation
Simple form
I could not engineer you could not engineer he could not engineer we could not engineer you could not engineer they could not engineer
V-ing form
I could not be engineering you could not be engineering he could not be engineering we could not be engineering you could not be engineering they could not be engineering
Perfect
I could not have engineered you could not have engineered he could not have engineered we could not have engineered you could not have engineered they could not have engineered
V-ing perfect
I could not have been engineering you could not have been engineering he could not have been engineering we could not have been engineering you could not have been engineering they could not have been engineering
Interrogative form
Simple form
could I engineer? could you engineer? could he engineer? could we engineer? could you engineer? could they engineer?
V-ing form
could I be engineering? could you be engineering? could he be engineering? could we be engineering? could you be engineering? could they be engineering?
Perfect
could I have engineered? could you have engineered? could he have engineered? could we have engineered? could you have engineered? could they have engineered?
V-ing perfect
could I have been engineering? could you have been engineering? could he have been engineering? could we have been engineering? could you have been engineering? could they have been engineering?
Interro-negative form
Simple form
could I not engineer? could you not engineer? could he not engineer? could we not engineer? could you not engineer? could they not engineer?
V-ing form
could I not be engineering? could you not be engineering? could he not be engineering? could we not be engineering? could you not be engineering? could they not be engineering?
Perfect
could I not have engineered? could you not have engineered? could he not have engineered? could we not have engineered? could you not have engineered? could they not have engineered?
V-ing perfect
could I not have been engineering? could you not have been engineering? could he not have been engineering? could we not have been engineering? could you not have been engineering? could they not have been engineering?