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