English verb conjugation
CAN GRUB

Regular verb: grub - grubbed - grubbed

Affirmation

Simple form	V-ing form
I can grub you can grub he can grub we can grub you can grub they can grub	I can be grubbing you can be grubbing he can be grubbing we can be grubbing you can be grubbing they can be grubbing
Perfect	V-ing perfect
I can have grubbed you can have grubbed he can have grubbed we can have grubbed you can have grubbed they can have grubbed	I can have been grubbing you can have been grubbing he can have been grubbing we can have been grubbing you can have been grubbing they can have been grubbing

Negation

Simple form	V-ing form
I can't grub you can't grub he can't grub we can't grub you can't grub they can't grub	I can't be grubbing you can't be grubbing he can't be grubbing we can't be grubbing you can't be grubbing they can't be grubbing
Perfect	V-ing perfect
I can't have grubbed you can't have grubbed he can't have grubbed we can't have grubbed you can't have grubbed they can't have grubbed	I can't have been grubbing you can't have been grubbing he can't have been grubbing we can't have been grubbing you can't have been grubbing they can't have been grubbing

Interrogative form

Simple form	V-ing form
can I grub? can you grub? can he grub? can we grub? can you grub? can they grub?	can I be grubbing? can you be grubbing? can he be grubbing? can we be grubbing? can you be grubbing? can they be grubbing?
Perfect	V-ing perfect
can I have grubbed? can you have grubbed? can he have grubbed? can we have grubbed? can you have grubbed? can they have grubbed?	can I have been grubbing? can you have been grubbing? can he have been grubbing? can we have been grubbing? can you have been grubbing? can they have been grubbing?

Interro-negative form

Simple form	V-ing form
can't I grub? can't you grub? can't he grub? can't we grub? can't you grub? can't they grub?	can't I be grubbing? can't you be grubbing? can't he be grubbing? can't we be grubbing? can't you be grubbing? can't they be grubbing?
Perfect	V-ing perfect
can't I have grubbed? can't you have grubbed? can't he have grubbed? can't we have grubbed? can't you have grubbed? can't they have grubbed?	can't I have been grubbing? can't you have been grubbing? can't he have been grubbing? can't we have been grubbing? can't you have been grubbing? can't they have been grubbing?