I could backsolve you could backsolve he could backsolve we could backsolve you could backsolve they could backsolve
V-ing form
I could be backsolving you could be backsolving he could be backsolving we could be backsolving you could be backsolving they could be backsolving
Perfect
I could have backsolved you could have backsolved he could have backsolved we could have backsolved you could have backsolved they could have backsolved
V-ing perfect
I could have been backsolving you could have been backsolving he could have been backsolving we could have been backsolving you could have been backsolving they could have been backsolving
Negation
Simple form
I could not backsolve you could not backsolve he could not backsolve we could not backsolve you could not backsolve they could not backsolve
V-ing form
I could not be backsolving you could not be backsolving he could not be backsolving we could not be backsolving you could not be backsolving they could not be backsolving
Perfect
I could not have backsolved you could not have backsolved he could not have backsolved we could not have backsolved you could not have backsolved they could not have backsolved
V-ing perfect
I could not have been backsolving you could not have been backsolving he could not have been backsolving we could not have been backsolving you could not have been backsolving they could not have been backsolving
Interrogative form
Simple form
could I backsolve? could you backsolve? could he backsolve? could we backsolve? could you backsolve? could they backsolve?
V-ing form
could I be backsolving? could you be backsolving? could he be backsolving? could we be backsolving? could you be backsolving? could they be backsolving?
Perfect
could I have backsolved? could you have backsolved? could he have backsolved? could we have backsolved? could you have backsolved? could they have backsolved?
V-ing perfect
could I have been backsolving? could you have been backsolving? could he have been backsolving? could we have been backsolving? could you have been backsolving? could they have been backsolving?
Interro-negative form
Simple form
could I not backsolve? could you not backsolve? could he not backsolve? could we not backsolve? could you not backsolve? could they not backsolve?
V-ing form
could I not be backsolving? could you not be backsolving? could he not be backsolving? could we not be backsolving? could you not be backsolving? could they not be backsolving?
Perfect
could I not have backsolved? could you not have backsolved? could he not have backsolved? could we not have backsolved? could you not have backsolved? could they not have backsolved?
V-ing perfect
could I not have been backsolving? could you not have been backsolving? could he not have been backsolving? could we not have been backsolving? could you not have been backsolving? could they not have been backsolving?