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