I must shift you must shift he must shift we must shift you must shift they must shift
V-ing form
I must be shifting you must be shifting he must be shifting we must be shifting you must be shifting they must be shifting
Perfect
I must have shifted you must have shifted he must have shifted we must have shifted you must have shifted they must have shifted
V-ing perfect
I must have been shifting you must have been shifting he must have been shifting we must have been shifting you must have been shifting they must have been shifting
Negation
Simple form
I must not shift you must not shift he must not shift we must not shift you must not shift they must not shift
V-ing form
I must not be shifting you must not be shifting he must not be shifting we must not be shifting you must not be shifting they must not be shifting
Perfect
I must not have shifted you must not have shifted he must not have shifted we must not have shifted you must not have shifted they must not have shifted
V-ing perfect
I must not have been shifting you must not have been shifting he must not have been shifting we must not have been shifting you must not have been shifting they must not have been shifting
Interrogative form
Simple form
must I shift? must you shift? must he shift? must we shift? must you shift? must they shift?
V-ing form
must I be shifting? must you be shifting? must he be shifting? must we be shifting? must you be shifting? must they be shifting?
Perfect
must I have shifted? must you have shifted? must he have shifted? must we have shifted? must you have shifted? must they have shifted?
V-ing perfect
must I have been shifting? must you have been shifting? must he have been shifting? must we have been shifting? must you have been shifting? must they have been shifting?
Interro-negative form
Simple form
must I not shift? must you not shift? must he not shift? must we not shift? must you not shift? must they not shift?
V-ing form
must I not be shifting? must you not be shifting? must he not be shifting? must we not be shifting? must you not be shifting? must they not be shifting?
Perfect
must I not have shifted? must you not have shifted? must he not have shifted? must we not have shifted? must you not have shifted? must they not have shifted?
V-ing perfect
must I not have been shifting? must you not have been shifting? must he not have been shifting? must we not have been shifting? must you not have been shifting? must they not have been shifting?