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