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 mustn't solve you mustn't solve he mustn't solve we mustn't solve you mustn't solve they mustn't solve
V-ing form
I mustn't be solving you mustn't be solving he mustn't be solving we mustn't be solving you mustn't be solving they mustn't be solving
Perfect
I mustn't have solved you mustn't have solved he mustn't have solved we mustn't have solved you mustn't have solved they mustn't have solved
V-ing perfect
I mustn't have been solving you mustn't have been solving he mustn't have been solving we mustn't have been solving you mustn't have been solving they mustn't 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
mustn't I solve? mustn't you solve? mustn't he solve? mustn't we solve? mustn't you solve? mustn't they solve?
V-ing form
mustn't I be solving? mustn't you be solving? mustn't he be solving? mustn't we be solving? mustn't you be solving? mustn't they be solving?
Perfect
mustn't I have solved? mustn't you have solved? mustn't he have solved? mustn't we have solved? mustn't you have solved? mustn't they have solved?
V-ing perfect
mustn't I have been solving? mustn't you have been solving? mustn't he have been solving? mustn't we have been solving? mustn't you have been solving? mustn't they have been solving?