I must dupe you must dupe he must dupe we must dupe you must dupe they must dupe
V-ing form
I must be duping you must be duping he must be duping we must be duping you must be duping they must be duping
Perfect
I must have duped you must have duped he must have duped we must have duped you must have duped they must have duped
V-ing perfect
I must have been duping you must have been duping he must have been duping we must have been duping you must have been duping they must have been duping
Negation
Simple form
I must not dupe you must not dupe he must not dupe we must not dupe you must not dupe they must not dupe
V-ing form
I must not be duping you must not be duping he must not be duping we must not be duping you must not be duping they must not be duping
Perfect
I must not have duped you must not have duped he must not have duped we must not have duped you must not have duped they must not have duped
V-ing perfect
I must not have been duping you must not have been duping he must not have been duping we must not have been duping you must not have been duping they must not have been duping
Interrogative form
Simple form
must I dupe? must you dupe? must he dupe? must we dupe? must you dupe? must they dupe?
V-ing form
must I be duping? must you be duping? must he be duping? must we be duping? must you be duping? must they be duping?
Perfect
must I have duped? must you have duped? must he have duped? must we have duped? must you have duped? must they have duped?
V-ing perfect
must I have been duping? must you have been duping? must he have been duping? must we have been duping? must you have been duping? must they have been duping?
Interro-negative form
Simple form
must I not dupe? must you not dupe? must he not dupe? must we not dupe? must you not dupe? must they not dupe?
V-ing form
must I not be duping? must you not be duping? must he not be duping? must we not be duping? must you not be duping? must they not be duping?
Perfect
must I not have duped? must you not have duped? must he not have duped? must we not have duped? must you not have duped? must they not have duped?
V-ing perfect
must I not have been duping? must you not have been duping? must he not have been duping? must we not have been duping? must you not have been duping? must they not have been duping?