I could grumble you could grumble she could grumble we could grumble you could grumble they could grumble
V-ing form
I could be grumbling you could be grumbling she could be grumbling we could be grumbling you could be grumbling they could be grumbling
Perfect
I could have grumbled you could have grumbled she could have grumbled we could have grumbled you could have grumbled they could have grumbled
V-ing perfect
I could have been grumbling you could have been grumbling she could have been grumbling we could have been grumbling you could have been grumbling they could have been grumbling
Negation
Simple form
I couldn't grumble you couldn't grumble she couldn't grumble we couldn't grumble you couldn't grumble they couldn't grumble
V-ing form
I couldn't be grumbling you couldn't be grumbling she couldn't be grumbling we couldn't be grumbling you couldn't be grumbling they couldn't be grumbling
Perfect
I couldn't have grumbled you couldn't have grumbled she couldn't have grumbled we couldn't have grumbled you couldn't have grumbled they couldn't have grumbled
V-ing perfect
I couldn't have been grumbling you couldn't have been grumbling she couldn't have been grumbling we couldn't have been grumbling you couldn't have been grumbling they couldn't have been grumbling
Interrogative form
Simple form
could I grumble? could you grumble? could she grumble? could we grumble? could you grumble? could they grumble?
V-ing form
could I be grumbling? could you be grumbling? could she be grumbling? could we be grumbling? could you be grumbling? could they be grumbling?
Perfect
could I have grumbled? could you have grumbled? could she have grumbled? could we have grumbled? could you have grumbled? could they have grumbled?
V-ing perfect
could I have been grumbling? could you have been grumbling? could she have been grumbling? could we have been grumbling? could you have been grumbling? could they have been grumbling?
Interro-negative form
Simple form
couldn't I grumble? couldn't you grumble? couldn't she grumble? couldn't we grumble? couldn't you grumble? couldn't they grumble?
V-ing form
couldn't I be grumbling? couldn't you be grumbling? couldn't she be grumbling? couldn't we be grumbling? couldn't you be grumbling? couldn't they be grumbling?
Perfect
couldn't I have grumbled? couldn't you have grumbled? couldn't she have grumbled? couldn't we have grumbled? couldn't you have grumbled? couldn't they have grumbled?
V-ing perfect
couldn't I have been grumbling? couldn't you have been grumbling? couldn't she have been grumbling? couldn't we have been grumbling? couldn't you have been grumbling? couldn't they have been grumbling?