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 must not slither you must not slither he must not slither we must not slither you must not slither they must not slither
V-ing form
I must not be slithering you must not be slithering he must not be slithering we must not be slithering you must not be slithering they must not be slithering
Perfect
I must not have slithered you must not have slithered he must not have slithered we must not have slithered you must not have slithered they must not have slithered
V-ing perfect
I must not have been slithering you must not have been slithering he must not have been slithering we must not have been slithering you must not have been slithering they must not 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
must I not slither? must you not slither? must he not slither? must we not slither? must you not slither? must they not slither?
V-ing form
must I not be slithering? must you not be slithering? must he not be slithering? must we not be slithering? must you not be slithering? must they not be slithering?
Perfect
must I not have slithered? must you not have slithered? must he not have slithered? must we not have slithered? must you not have slithered? must they not have slithered?
V-ing perfect
must I not have been slithering? must you not have been slithering? must he not have been slithering? must we not have been slithering? must you not have been slithering? must they not have been slithering?