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