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