I must center you must center he must center we must center you must center they must center
V-ing form
I must be centering you must be centering he must be centering we must be centering you must be centering they must be centering
Perfect
I must have centered you must have centered he must have centered we must have centered you must have centered they must have centered
V-ing perfect
I must have been centering you must have been centering he must have been centering we must have been centering you must have been centering they must have been centering
Negation
Simple form
I mustn't center you mustn't center he mustn't center we mustn't center you mustn't center they mustn't center
V-ing form
I mustn't be centering you mustn't be centering he mustn't be centering we mustn't be centering you mustn't be centering they mustn't be centering
Perfect
I mustn't have centered you mustn't have centered he mustn't have centered we mustn't have centered you mustn't have centered they mustn't have centered
V-ing perfect
I mustn't have been centering you mustn't have been centering he mustn't have been centering we mustn't have been centering you mustn't have been centering they mustn't have been centering
Interrogative form
Simple form
must I center? must you center? must he center? must we center? must you center? must they center?
V-ing form
must I be centering? must you be centering? must he be centering? must we be centering? must you be centering? must they be centering?
Perfect
must I have centered? must you have centered? must he have centered? must we have centered? must you have centered? must they have centered?
V-ing perfect
must I have been centering? must you have been centering? must he have been centering? must we have been centering? must you have been centering? must they have been centering?
Interro-negative form
Simple form
mustn't I center? mustn't you center? mustn't he center? mustn't we center? mustn't you center? mustn't they center?
V-ing form
mustn't I be centering? mustn't you be centering? mustn't he be centering? mustn't we be centering? mustn't you be centering? mustn't they be centering?
Perfect
mustn't I have centered? mustn't you have centered? mustn't he have centered? mustn't we have centered? mustn't you have centered? mustn't they have centered?
V-ing perfect
mustn't I have been centering? mustn't you have been centering? mustn't he have been centering? mustn't we have been centering? mustn't you have been centering? mustn't they have been centering?