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