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