must backsolve
Regular verb: backsolve - backsolved- backsolved

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must backsolve
you must backsolve
he must backsolve
we must backsolve
you must backsolve
they must backsolve 	I must be backsolving
you must be backsolving
he must be backsolving
we must be backsolving
you must be backsolving
they must be backsolving	I must have backsolved
you must have backsolved
he must have backsolved
we must have backsolved
you must have backsolved
they must have backsolved	I must have been backsolving
you must have been backsolving
he must have been backsolving
we must have been backsolving
you must have been backsolving
they must have been backsolving	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not backsolve
you must not backsolve
he must not backsolve
we must not backsolve
you must not backsolve
they must not backsolve 	I must not be backsolving
you must not be backsolving
he must not be backsolving
we must not be backsolving
you must not be backsolving
they must not be backsolving	I must not have backsolved
you must not have backsolved
he must not have backsolved
we must not have backsolved
you must not have backsolved
they must not have backsolved	I must not have been backsolving
you must not have been backsolving
he must not have been backsolving
we must not have been backsolving
you must not have been backsolving
they must not have been backsolving	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I backsolve?
must you backsolve?
must he backsolve?
must we backsolve?
must you backsolve?
must they backsolve? 	must I be backsolving?
must you be backsolving?
must he be backsolving?
must we be backsolving?
must you be backsolving?
must they be backsolving? 	must I have backsolved?
must you have backsolved?
must he have backsolved?
must we have backsolved?
must you have backsolved?
must they have backsolved? 	must I have been backsolving?
must you have been backsolving?
must he have been backsolving?
must we have been backsolving?
must you have been backsolving?
must they have been backsolving? 	

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