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