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