I could tidy you could tidy he could tidy we could tidy you could tidy they could tidy
V-ing form
I could be tidying you could be tidying he could be tidying we could be tidying you could be tidying they could be tidying
Perfect
I could have tidied you could have tidied he 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 he could have been tidying we could have been tidying you could have been tidying they could have been tidying
Negation
Simple form
I couldn't tidy you couldn't tidy he couldn't tidy we couldn't tidy you couldn't tidy they couldn't tidy
V-ing form
I couldn't be tidying you couldn't be tidying he couldn't be tidying we couldn't be tidying you couldn't be tidying they couldn't be tidying
Perfect
I couldn't have tidied you couldn't have tidied he couldn't have tidied we couldn't have tidied you couldn't have tidied they couldn't have tidied
V-ing perfect
I couldn't have been tidying you couldn't have been tidying he couldn't have been tidying we couldn't have been tidying you couldn't have been tidying they couldn't have been tidying
Interrogative form
Simple form
could I tidy? could you tidy? could he tidy? could we tidy? could you tidy? could they tidy?
V-ing form
could I be tidying? could you be tidying? could he be tidying? could we be tidying? could you be tidying? could they be tidying?
Perfect
could I have tidied? could you have tidied? could he 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 he have been tidying? could we have been tidying? could you have been tidying? could they have been tidying?
Interro-negative form
Simple form
couldn't I tidy? couldn't you tidy? couldn't he tidy? couldn't we tidy? couldn't you tidy? couldn't they tidy?
V-ing form
couldn't I be tidying? couldn't you be tidying? couldn't he be tidying? couldn't we be tidying? couldn't you be tidying? couldn't they be tidying?
Perfect
couldn't I have tidied? couldn't you have tidied? couldn't he have tidied? couldn't we have tidied? couldn't you have tidied? couldn't they have tidied?
V-ing perfect
couldn't I have been tidying? couldn't you have been tidying? couldn't he have been tidying? couldn't we have been tidying? couldn't you have been tidying? couldn't they have been tidying?