I must prolong you must prolong he must prolong we must prolong you must prolong they must prolong
V-ing form
I must be prolonging you must be prolonging he must be prolonging we must be prolonging you must be prolonging they must be prolonging
Perfect
I must have prolonged you must have prolonged he must have prolonged we must have prolonged you must have prolonged they must have prolonged
V-ing perfect
I must have been prolonging you must have been prolonging he must have been prolonging we must have been prolonging you must have been prolonging they must have been prolonging
Negation
Simple form
I must not prolong you must not prolong he must not prolong we must not prolong you must not prolong they must not prolong
V-ing form
I must not be prolonging you must not be prolonging he must not be prolonging we must not be prolonging you must not be prolonging they must not be prolonging
Perfect
I must not have prolonged you must not have prolonged he must not have prolonged we must not have prolonged you must not have prolonged they must not have prolonged
V-ing perfect
I must not have been prolonging you must not have been prolonging he must not have been prolonging we must not have been prolonging you must not have been prolonging they must not have been prolonging
Interrogative form
Simple form
must I prolong? must you prolong? must he prolong? must we prolong? must you prolong? must they prolong?
V-ing form
must I be prolonging? must you be prolonging? must he be prolonging? must we be prolonging? must you be prolonging? must they be prolonging?
Perfect
must I have prolonged? must you have prolonged? must he have prolonged? must we have prolonged? must you have prolonged? must they have prolonged?
V-ing perfect
must I have been prolonging? must you have been prolonging? must he have been prolonging? must we have been prolonging? must you have been prolonging? must they have been prolonging?
Interro-negative form
Simple form
must I not prolong? must you not prolong? must he not prolong? must we not prolong? must you not prolong? must they not prolong?
V-ing form
must I not be prolonging? must you not be prolonging? must he not be prolonging? must we not be prolonging? must you not be prolonging? must they not be prolonging?
Perfect
must I not have prolonged? must you not have prolonged? must he not have prolonged? must we not have prolonged? must you not have prolonged? must they not have prolonged?
V-ing perfect
must I not have been prolonging? must you not have been prolonging? must he not have been prolonging? must we not have been prolonging? must you not have been prolonging? must they not have been prolonging?