I must gnaw you must gnaw he must gnaw we must gnaw you must gnaw they must gnaw
V-ing form
I must be gnawing you must be gnawing he must be gnawing we must be gnawing you must be gnawing they must be gnawing
Perfect
I must have gnawed you must have gnawed he must have gnawed we must have gnawed you must have gnawed they must have gnawed
V-ing perfect
I must have been gnawing you must have been gnawing he must have been gnawing we must have been gnawing you must have been gnawing they must have been gnawing
Negation
Simple form
I mustn't gnaw you mustn't gnaw he mustn't gnaw we mustn't gnaw you mustn't gnaw they mustn't gnaw
V-ing form
I mustn't be gnawing you mustn't be gnawing he mustn't be gnawing we mustn't be gnawing you mustn't be gnawing they mustn't be gnawing
Perfect
I mustn't have gnawed you mustn't have gnawed he mustn't have gnawed we mustn't have gnawed you mustn't have gnawed they mustn't have gnawed
V-ing perfect
I mustn't have been gnawing you mustn't have been gnawing he mustn't have been gnawing we mustn't have been gnawing you mustn't have been gnawing they mustn't have been gnawing
Interrogative form
Simple form
must I gnaw? must you gnaw? must he gnaw? must we gnaw? must you gnaw? must they gnaw?
V-ing form
must I be gnawing? must you be gnawing? must he be gnawing? must we be gnawing? must you be gnawing? must they be gnawing?
Perfect
must I have gnawed? must you have gnawed? must he have gnawed? must we have gnawed? must you have gnawed? must they have gnawed?
V-ing perfect
must I have been gnawing? must you have been gnawing? must he have been gnawing? must we have been gnawing? must you have been gnawing? must they have been gnawing?
Interro-negative form
Simple form
mustn't I gnaw? mustn't you gnaw? mustn't he gnaw? mustn't we gnaw? mustn't you gnaw? mustn't they gnaw?
V-ing form
mustn't I be gnawing? mustn't you be gnawing? mustn't he be gnawing? mustn't we be gnawing? mustn't you be gnawing? mustn't they be gnawing?
Perfect
mustn't I have gnawed? mustn't you have gnawed? mustn't he have gnawed? mustn't we have gnawed? mustn't you have gnawed? mustn't they have gnawed?
V-ing perfect
mustn't I have been gnawing? mustn't you have been gnawing? mustn't he have been gnawing? mustn't we have been gnawing? mustn't you have been gnawing? mustn't they have been gnawing?