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