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