I must burrow you must burrow he must burrow we must burrow you must burrow they must burrow
V-ing form
I must be burrowing you must be burrowing he must be burrowing we must be burrowing you must be burrowing they must be burrowing
Perfect
I must have burrowed you must have burrowed he must have burrowed we must have burrowed you must have burrowed they must have burrowed
V-ing perfect
I must have been burrowing you must have been burrowing he must have been burrowing we must have been burrowing you must have been burrowing they must have been burrowing
Negation
Simple form
I must not burrow you must not burrow he must not burrow we must not burrow you must not burrow they must not burrow
V-ing form
I must not be burrowing you must not be burrowing he must not be burrowing we must not be burrowing you must not be burrowing they must not be burrowing
Perfect
I must not have burrowed you must not have burrowed he must not have burrowed we must not have burrowed you must not have burrowed they must not have burrowed
V-ing perfect
I must not have been burrowing you must not have been burrowing he must not have been burrowing we must not have been burrowing you must not have been burrowing they must not have been burrowing
Interrogative form
Simple form
must I burrow? must you burrow? must he burrow? must we burrow? must you burrow? must they burrow?
V-ing form
must I be burrowing? must you be burrowing? must he be burrowing? must we be burrowing? must you be burrowing? must they be burrowing?
Perfect
must I have burrowed? must you have burrowed? must he have burrowed? must we have burrowed? must you have burrowed? must they have burrowed?
V-ing perfect
must I have been burrowing? must you have been burrowing? must he have been burrowing? must we have been burrowing? must you have been burrowing? must they have been burrowing?
Interro-negative form
Simple form
must I not burrow? must you not burrow? must he not burrow? must we not burrow? must you not burrow? must they not burrow?
V-ing form
must I not be burrowing? must you not be burrowing? must he not be burrowing? must we not be burrowing? must you not be burrowing? must they not be burrowing?
Perfect
must I not have burrowed? must you not have burrowed? must he not have burrowed? must we not have burrowed? must you not have burrowed? must they not have burrowed?
V-ing perfect
must I not have been burrowing? must you not have been burrowing? must he not have been burrowing? must we not have been burrowing? must you not have been burrowing? must they not have been burrowing?