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