I must solve you must solve he must solve we must solve you must solve they must solve
Forma con V-ing
I must be solving you must be solving he must be solving we must be solving you must be solving they must be solving
Perfecto
I must have solved you must have solved he must have solved we must have solved you must have solved they must have solved
Perfecto con V-ing
I must have been solving you must have been solving he must have been solving we must have been solving you must have been solving they must have been solving
Negación
Forma simple
I must not solve you must not solve he must not solve we must not solve you must not solve they must not solve
Forma con V-ing
I must not be solving you must not be solving he must not be solving we must not be solving you must not be solving they must not be solving
Perfecto
I must not have solved you must not have solved he must not have solved we must not have solved you must not have solved they must not have solved
Perfecto con V-ing
I must not have been solving you must not have been solving he must not have been solving we must not have been solving you must not have been solving they must not have been solving
Forma interrogativa
Forma simple
must I solve? must you solve? must he solve? must we solve? must you solve? must they solve?
Forma con V-ing
must I be solving? must you be solving? must he be solving? must we be solving? must you be solving? must they be solving?
Perfecto
must I have solved? must you have solved? must he have solved? must we have solved? must you have solved? must they have solved?
Perfecto con V-ing
must I have been solving? must you have been solving? must he have been solving? must we have been solving? must you have been solving? must they have been solving?
Forma interro-negativa
Forma simple
must I not solve? must you not solve? must he not solve? must we not solve? must you not solve? must they not solve?
Forma con V-ing
must I not be solving? must you not be solving? must he not be solving? must we not be solving? must you not be solving? must they not be solving?
Perfecto
must I not have solved? must you not have solved? must he not have solved? must we not have solved? must you not have solved? must they not have solved?
Perfecto con V-ing
must I not have been solving? must you not have been solving? must he not have been solving? must we not have been solving? must you not have been solving? must they not have been solving?