must grubstake
Regular verb: grubstake - grubstaked- grubstaked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must grubstake
you must grubstake
she must grubstake
we must grubstake
you must grubstake
they must grubstake 	I must be grubstaking
you must be grubstaking
she must be grubstaking
we must be grubstaking
you must be grubstaking
they must be grubstaking	I must have grubstaked
you must have grubstaked
she 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
she 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 mustn't grubstake
you mustn't grubstake
she mustn't grubstake
we mustn't grubstake
you mustn't grubstake
they mustn't grubstake 	I mustn't be grubstaking
you mustn't be grubstaking
she mustn't be grubstaking
we mustn't be grubstaking
you mustn't be grubstaking
they mustn't be grubstaking	I mustn't have grubstaked
you mustn't have grubstaked
she mustn't have grubstaked
we mustn't have grubstaked
you mustn't have grubstaked
they mustn't have grubstaked	I mustn't have been grubstaking
you mustn't have been grubstaking
she mustn't have been grubstaking
we mustn't have been grubstaking
you mustn't have been grubstaking
they mustn't have been grubstaking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I grubstake?
must you grubstake?
must she grubstake?
must we grubstake?
must you grubstake?
must they grubstake? 	must I be grubstaking?
must you be grubstaking?
must she be grubstaking?
must we be grubstaking?
must you be grubstaking?
must they be grubstaking? 	must I have grubstaked?
must you have grubstaked?
must she 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 she 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 	
mustn't I grubstake?
mustn't you grubstake?
mustn't she grubstake?
mustn't we grubstake?
mustn't you grubstake?
mustn't they grubstake? 	mustn't I be grubstaking?
mustn't you be grubstaking?
mustn't she be grubstaking?
mustn't we be grubstaking?
mustn't you be grubstaking?
mustn't they be grubstaking? 	mustn't I have grubstaked?
mustn't you have grubstaked?
mustn't she have grubstaked?
mustn't we have grubstaked?
mustn't you have grubstaked?
mustn't they have grubstaked? 	mustn't I have been grubstaking?
mustn't you have been grubstaking?
mustn't she have been grubstaking?
mustn't we have been grubstaking?
mustn't you have been grubstaking?
mustn't they have been grubstaking?