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