I must skip you must skip she must skip we must skip you must skip they must skip
V-ing form
I must be skipping you must be skipping she must be skipping we must be skipping you must be skipping they must be skipping
Perfect
I must have skipped you must have skipped she must have skipped we must have skipped you must have skipped they must have skipped
V-ing perfect
I must have been skipping you must have been skipping she must have been skipping we must have been skipping you must have been skipping they must have been skipping
Negation
Simple form
I mustn't skip you mustn't skip she mustn't skip we mustn't skip you mustn't skip they mustn't skip
V-ing form
I mustn't be skipping you mustn't be skipping she mustn't be skipping we mustn't be skipping you mustn't be skipping they mustn't be skipping
Perfect
I mustn't have skipped you mustn't have skipped she mustn't have skipped we mustn't have skipped you mustn't have skipped they mustn't have skipped
V-ing perfect
I mustn't have been skipping you mustn't have been skipping she mustn't have been skipping we mustn't have been skipping you mustn't have been skipping they mustn't have been skipping
Interrogative form
Simple form
must I skip? must you skip? must she skip? must we skip? must you skip? must they skip?
V-ing form
must I be skipping? must you be skipping? must she be skipping? must we be skipping? must you be skipping? must they be skipping?
Perfect
must I have skipped? must you have skipped? must she have skipped? must we have skipped? must you have skipped? must they have skipped?
V-ing perfect
must I have been skipping? must you have been skipping? must she have been skipping? must we have been skipping? must you have been skipping? must they have been skipping?
Interro-negative form
Simple form
mustn't I skip? mustn't you skip? mustn't she skip? mustn't we skip? mustn't you skip? mustn't they skip?
V-ing form
mustn't I be skipping? mustn't you be skipping? mustn't she be skipping? mustn't we be skipping? mustn't you be skipping? mustn't they be skipping?
Perfect
mustn't I have skipped? mustn't you have skipped? mustn't she have skipped? mustn't we have skipped? mustn't you have skipped? mustn't they have skipped?
V-ing perfect
mustn't I have been skipping? mustn't you have been skipping? mustn't she have been skipping? mustn't we have been skipping? mustn't you have been skipping? mustn't they have been skipping?