I can grumble you can grumble he can grumble we can grumble you can grumble they can grumble
V-ing form
I can be grumbling you can be grumbling he can be grumbling we can be grumbling you can be grumbling they can be grumbling
Perfect
I can have grumbled you can have grumbled he can have grumbled we can have grumbled you can have grumbled they can have grumbled
V-ing perfect
I can have been grumbling you can have been grumbling he can have been grumbling we can have been grumbling you can have been grumbling they can have been grumbling
Negation
Simple form
I cannot grumble you cannot grumble he cannot grumble we cannot grumble you cannot grumble they cannot grumble
V-ing form
I cannot be grumbling you cannot be grumbling he cannot be grumbling we cannot be grumbling you cannot be grumbling they cannot be grumbling
Perfect
I cannot have grumbled you cannot have grumbled he cannot have grumbled we cannot have grumbled you cannot have grumbled they cannot have grumbled
V-ing perfect
I cannot have been grumbling you cannot have been grumbling he cannot have been grumbling we cannot have been grumbling you cannot have been grumbling they cannot have been grumbling
Interrogative form
Simple form
can I grumble? can you grumble? can he grumble? can we grumble? can you grumble? can they grumble?
V-ing form
can I be grumbling? can you be grumbling? can he be grumbling? can we be grumbling? can you be grumbling? can they be grumbling?
Perfect
can I have grumbled? can you have grumbled? can he have grumbled? can we have grumbled? can you have grumbled? can they have grumbled?
V-ing perfect
can I have been grumbling? can you have been grumbling? can he have been grumbling? can we have been grumbling? can you have been grumbling? can they have been grumbling?
Interro-negative form
Simple form
can I not grumble? can you not grumble? can he not grumble? can we not grumble? can you not grumble? can they not grumble?
V-ing form
can I not be grumbling? can you not be grumbling? can he not be grumbling? can we not be grumbling? can you not be grumbling? can they not be grumbling?
Perfect
can I not have grumbled? can you not have grumbled? can he not have grumbled? can we not have grumbled? can you not have grumbled? can they not have grumbled?
V-ing perfect
can I not have been grumbling? can you not have been grumbling? can he not have been grumbling? can we not have been grumbling? can you not have been grumbling? can they not have been grumbling?