I must center you must center she must center we must center you must center they must center
V-ing form
I must be centering you must be centering she must be centering we must be centering you must be centering they must be centering
Perfect
I must have centered you must have centered she 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 she must have been centering we must have been centering you must have been centering they must have been centering
Negation
Simple form
I must not center you must not center she must not center we must not center you must not center they must not center
V-ing form
I must not be centering you must not be centering she must not be centering we must not be centering you must not be centering they must not be centering
Perfect
I must not have centered you must not have centered she must not have centered we must not have centered you must not have centered they must not have centered
V-ing perfect
I must not have been centering you must not have been centering she must not have been centering we must not have been centering you must not have been centering they must not have been centering
Interrogative form
Simple form
must I center? must you center? must she center? must we center? must you center? must they center?
V-ing form
must I be centering? must you be centering? must she be centering? must we be centering? must you be centering? must they be centering?
Perfect
must I have centered? must you have centered? must she 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 she have been centering? must we have been centering? must you have been centering? must they have been centering?
Interro-negative form
Simple form
must I not center? must you not center? must she not center? must we not center? must you not center? must they not center?
V-ing form
must I not be centering? must you not be centering? must she not be centering? must we not be centering? must you not be centering? must they not be centering?
Perfect
must I not have centered? must you not have centered? must she not have centered? must we not have centered? must you not have centered? must they not have centered?
V-ing perfect
must I not have been centering? must you not have been centering? must she not have been centering? must we not have been centering? must you not have been centering? must they not have been centering?