I must solve you must solve he must solve we must solve you must solve they must solve
V-ing form
I must be solving you must be solving he must be solving we must be solving you must be solving they must be solving
Perfect
I must have solved you must have solved he must have solved we must have solved you must have solved they must have solved
V-ing perfect
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
Negation
Simple form
I must not solve you must not solve he must not solve we must not solve you must not solve they must not solve
V-ing form
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
Perfect
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
V-ing perfect
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
Interrogative form
Simple form
must I solve? must you solve? must he solve? must we solve? must you solve? must they solve?
V-ing form
must I be solving? must you be solving? must he be solving? must we be solving? must you be solving? must they be solving?
Perfect
must I have solved? must you have solved? must he have solved? must we have solved? must you have solved? must they have solved?
V-ing perfect
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?
Interro-negative form
Simple form
must I not solve? must you not solve? must he not solve? must we not solve? must you not solve? must they not solve?
V-ing form
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?
Perfect
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?
V-ing perfect
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?