I must sough you must sough she must sough we must sough you must sough they must sough
V-ing form
I must be soughing you must be soughing she must be soughing we must be soughing you must be soughing they must be soughing
Perfect
I must have soughed you must have soughed she must have soughed we must have soughed you must have soughed they must have soughed
V-ing perfect
I must have been soughing you must have been soughing she must have been soughing we must have been soughing you must have been soughing they must have been soughing
Negation
Simple form
I mustn't sough you mustn't sough she mustn't sough we mustn't sough you mustn't sough they mustn't sough
V-ing form
I mustn't be soughing you mustn't be soughing she mustn't be soughing we mustn't be soughing you mustn't be soughing they mustn't be soughing
Perfect
I mustn't have soughed you mustn't have soughed she mustn't have soughed we mustn't have soughed you mustn't have soughed they mustn't have soughed
V-ing perfect
I mustn't have been soughing you mustn't have been soughing she mustn't have been soughing we mustn't have been soughing you mustn't have been soughing they mustn't have been soughing
Interrogative form
Simple form
must I sough? must you sough? must she sough? must we sough? must you sough? must they sough?
V-ing form
must I be soughing? must you be soughing? must she be soughing? must we be soughing? must you be soughing? must they be soughing?
Perfect
must I have soughed? must you have soughed? must she have soughed? must we have soughed? must you have soughed? must they have soughed?
V-ing perfect
must I have been soughing? must you have been soughing? must she have been soughing? must we have been soughing? must you have been soughing? must they have been soughing?
Interro-negative form
Simple form
mustn't I sough? mustn't you sough? mustn't she sough? mustn't we sough? mustn't you sough? mustn't they sough?
V-ing form
mustn't I be soughing? mustn't you be soughing? mustn't she be soughing? mustn't we be soughing? mustn't you be soughing? mustn't they be soughing?
Perfect
mustn't I have soughed? mustn't you have soughed? mustn't she have soughed? mustn't we have soughed? mustn't you have soughed? mustn't they have soughed?
V-ing perfect
mustn't I have been soughing? mustn't you have been soughing? mustn't she have been soughing? mustn't we have been soughing? mustn't you have been soughing? mustn't they have been soughing?