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