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