I could tidy you could tidy she could tidy we could tidy you could tidy they could tidy
V-ing form
I could be tidying you could be tidying she could be tidying we could be tidying you could be tidying they could be tidying
Perfect
I could have tidied you could have tidied she could have tidied we could have tidied you could have tidied they could have tidied
V-ing perfect
I could have been tidying you could have been tidying she could have been tidying we could have been tidying you could have been tidying they could have been tidying
Negation
Simple form
I could not tidy you could not tidy she could not tidy we could not tidy you could not tidy they could not tidy
V-ing form
I could not be tidying you could not be tidying she could not be tidying we could not be tidying you could not be tidying they could not be tidying
Perfect
I could not have tidied you could not have tidied she could not have tidied we could not have tidied you could not have tidied they could not have tidied
V-ing perfect
I could not have been tidying you could not have been tidying she could not have been tidying we could not have been tidying you could not have been tidying they could not have been tidying
Interrogative form
Simple form
could I tidy? could you tidy? could she tidy? could we tidy? could you tidy? could they tidy?
V-ing form
could I be tidying? could you be tidying? could she be tidying? could we be tidying? could you be tidying? could they be tidying?
Perfect
could I have tidied? could you have tidied? could she have tidied? could we have tidied? could you have tidied? could they have tidied?
V-ing perfect
could I have been tidying? could you have been tidying? could she have been tidying? could we have been tidying? could you have been tidying? could they have been tidying?
Interro-negative form
Simple form
could I not tidy? could you not tidy? could she not tidy? could we not tidy? could you not tidy? could they not tidy?
V-ing form
could I not be tidying? could you not be tidying? could she not be tidying? could we not be tidying? could you not be tidying? could they not be tidying?
Perfect
could I not have tidied? could you not have tidied? could she not have tidied? could we not have tidied? could you not have tidied? could they not have tidied?
V-ing perfect
could I not have been tidying? could you not have been tidying? could she not have been tidying? could we not have been tidying? could you not have been tidying? could they not have been tidying?