I must preoccupy you must preoccupy he must preoccupy we must preoccupy you must preoccupy they must preoccupy
V-ing form
I must be preoccupying you must be preoccupying he must be preoccupying we must be preoccupying you must be preoccupying they must be preoccupying
Perfect
I must have preoccupied you must have preoccupied he must have preoccupied we must have preoccupied you must have preoccupied they must have preoccupied
V-ing perfect
I must have been preoccupying you must have been preoccupying he must have been preoccupying we must have been preoccupying you must have been preoccupying they must have been preoccupying
Negation
Simple form
I must not preoccupy you must not preoccupy he must not preoccupy we must not preoccupy you must not preoccupy they must not preoccupy
V-ing form
I must not be preoccupying you must not be preoccupying he must not be preoccupying we must not be preoccupying you must not be preoccupying they must not be preoccupying
Perfect
I must not have preoccupied you must not have preoccupied he must not have preoccupied we must not have preoccupied you must not have preoccupied they must not have preoccupied
V-ing perfect
I must not have been preoccupying you must not have been preoccupying he must not have been preoccupying we must not have been preoccupying you must not have been preoccupying they must not have been preoccupying
Interrogative form
Simple form
must I preoccupy? must you preoccupy? must he preoccupy? must we preoccupy? must you preoccupy? must they preoccupy?
V-ing form
must I be preoccupying? must you be preoccupying? must he be preoccupying? must we be preoccupying? must you be preoccupying? must they be preoccupying?
Perfect
must I have preoccupied? must you have preoccupied? must he have preoccupied? must we have preoccupied? must you have preoccupied? must they have preoccupied?
V-ing perfect
must I have been preoccupying? must you have been preoccupying? must he have been preoccupying? must we have been preoccupying? must you have been preoccupying? must they have been preoccupying?
Interro-negative form
Simple form
must I not preoccupy? must you not preoccupy? must he not preoccupy? must we not preoccupy? must you not preoccupy? must they not preoccupy?
V-ing form
must I not be preoccupying? must you not be preoccupying? must he not be preoccupying? must we not be preoccupying? must you not be preoccupying? must they not be preoccupying?
Perfect
must I not have preoccupied? must you not have preoccupied? must he not have preoccupied? must we not have preoccupied? must you not have preoccupied? must they not have preoccupied?
V-ing perfect
must I not have been preoccupying? must you not have been preoccupying? must he not have been preoccupying? must we not have been preoccupying? must you not have been preoccupying? must they not have been preoccupying?