I can backsolve you can backsolve she can backsolve we can backsolve you can backsolve they can backsolve
V-ing form
I can be backsolving you can be backsolving she can be backsolving we can be backsolving you can be backsolving they can be backsolving
Perfect
I can have backsolved you can have backsolved she 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 she 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 she 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 she 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 she 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 she 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 she backsolve? can we backsolve? can you backsolve? can they backsolve?
V-ing form
can I be backsolving? can you be backsolving? can she be backsolving? can we be backsolving? can you be backsolving? can they be backsolving?
Perfect
can I have backsolved? can you have backsolved? can she 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 she 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 she 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 she 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 she 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 she have been backsolving? can't we have been backsolving? can't you have been backsolving? can't they have been backsolving?