must grubstake
Regular verb: grubstake - grubstaked- grubstaked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must grubstake
you must grubstake
he must grubstake
we must grubstake
you must grubstake
they must grubstake 	I must be grubstaking
you must be grubstaking
he must be grubstaking
we must be grubstaking
you must be grubstaking
they must be grubstaking	I must have grubstaked
you must have grubstaked
he must have grubstaked
we must have grubstaked
you must have grubstaked
they must have grubstaked	I must have been grubstaking
you must have been grubstaking
he must have been grubstaking
we must have been grubstaking
you must have been grubstaking
they must have been grubstaking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not grubstake
you must not grubstake
he must not grubstake
we must not grubstake
you must not grubstake
they must not grubstake 	I must not be grubstaking
you must not be grubstaking
he must not be grubstaking
we must not be grubstaking
you must not be grubstaking
they must not be grubstaking	I must not have grubstaked
you must not have grubstaked
he must not have grubstaked
we must not have grubstaked
you must not have grubstaked
they must not have grubstaked	I must not have been grubstaking
you must not have been grubstaking
he must not have been grubstaking
we must not have been grubstaking
you must not have been grubstaking
they must not have been grubstaking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I grubstake?
must you grubstake?
must he grubstake?
must we grubstake?
must you grubstake?
must they grubstake? 	must I be grubstaking?
must you be grubstaking?
must he be grubstaking?
must we be grubstaking?
must you be grubstaking?
must they be grubstaking? 	must I have grubstaked?
must you have grubstaked?
must he have grubstaked?
must we have grubstaked?
must you have grubstaked?
must they have grubstaked? 	must I have been grubstaking?
must you have been grubstaking?
must he have been grubstaking?
must we have been grubstaking?
must you have been grubstaking?
must they have been grubstaking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not grubstake?
must you not grubstake?
must he not grubstake?
must we not grubstake?
must you not grubstake?
must they not grubstake? 	must I not be grubstaking?
must you not be grubstaking?
must he not be grubstaking?
must we not be grubstaking?
must you not be grubstaking?
must they not be grubstaking? 	must I not have grubstaked?
must you not have grubstaked?
must he not have grubstaked?
must we not have grubstaked?
must you not have grubstaked?
must they not have grubstaked? 	must I not have been grubstaking?
must you not have been grubstaking?
must he not have been grubstaking?
must we not have been grubstaking?
must you not have been grubstaking?
must they not have been grubstaking?