I must harp you must harp he must harp we must harp you must harp they must harp
V-ing form
I must be harping you must be harping he must be harping we must be harping you must be harping they must be harping
Perfect
I must have harped you must have harped he must have harped we must have harped you must have harped they must have harped
V-ing perfect
I must have been harping you must have been harping he must have been harping we must have been harping you must have been harping they must have been harping
Negation
Simple form
I must not harp you must not harp he must not harp we must not harp you must not harp they must not harp
V-ing form
I must not be harping you must not be harping he must not be harping we must not be harping you must not be harping they must not be harping
Perfect
I must not have harped you must not have harped he must not have harped we must not have harped you must not have harped they must not have harped
V-ing perfect
I must not have been harping you must not have been harping he must not have been harping we must not have been harping you must not have been harping they must not have been harping
Interrogative form
Simple form
must I harp? must you harp? must he harp? must we harp? must you harp? must they harp?
V-ing form
must I be harping? must you be harping? must he be harping? must we be harping? must you be harping? must they be harping?
Perfect
must I have harped? must you have harped? must he have harped? must we have harped? must you have harped? must they have harped?
V-ing perfect
must I have been harping? must you have been harping? must he have been harping? must we have been harping? must you have been harping? must they have been harping?
Interro-negative form
Simple form
must I not harp? must you not harp? must he not harp? must we not harp? must you not harp? must they not harp?
V-ing form
must I not be harping? must you not be harping? must he not be harping? must we not be harping? must you not be harping? must they not be harping?
Perfect
must I not have harped? must you not have harped? must he not have harped? must we not have harped? must you not have harped? must they not have harped?
V-ing perfect
must I not have been harping? must you not have been harping? must he not have been harping? must we not have been harping? must you not have been harping? must they not have been harping?