I must backstop you must backstop he must backstop we must backstop you must backstop they must backstop
V-ing form
I must be backstoping you must be backstoping he must be backstoping we must be backstoping you must be backstoping they must be backstoping
Perfect
I must have backstoped you must have backstoped he must have backstoped we must have backstoped you must have backstoped they must have backstoped
V-ing perfect
I must have been backstoping you must have been backstoping he must have been backstoping we must have been backstoping you must have been backstoping they must have been backstoping
Negation
Simple form
I must not backstop you must not backstop he must not backstop we must not backstop you must not backstop they must not backstop
V-ing form
I must not be backstoping you must not be backstoping he must not be backstoping we must not be backstoping you must not be backstoping they must not be backstoping
Perfect
I must not have backstoped you must not have backstoped he must not have backstoped we must not have backstoped you must not have backstoped they must not have backstoped
V-ing perfect
I must not have been backstoping you must not have been backstoping he must not have been backstoping we must not have been backstoping you must not have been backstoping they must not have been backstoping
Interrogative form
Simple form
must I backstop? must you backstop? must he backstop? must we backstop? must you backstop? must they backstop?
V-ing form
must I be backstoping? must you be backstoping? must he be backstoping? must we be backstoping? must you be backstoping? must they be backstoping?
Perfect
must I have backstoped? must you have backstoped? must he have backstoped? must we have backstoped? must you have backstoped? must they have backstoped?
V-ing perfect
must I have been backstoping? must you have been backstoping? must he have been backstoping? must we have been backstoping? must you have been backstoping? must they have been backstoping?
Interro-negative form
Simple form
must I not backstop? must you not backstop? must he not backstop? must we not backstop? must you not backstop? must they not backstop?
V-ing form
must I not be backstoping? must you not be backstoping? must he not be backstoping? must we not be backstoping? must you not be backstoping? must they not be backstoping?
Perfect
must I not have backstoped? must you not have backstoped? must he not have backstoped? must we not have backstoped? must you not have backstoped? must they not have backstoped?
V-ing perfect
must I not have been backstoping? must you not have been backstoping? must he not have been backstoping? must we not have been backstoping? must you not have been backstoping? must they not have been backstoping?