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