I could gross you could gross she could gross we could gross you could gross they could gross
V-ing form
I could be grossing you could be grossing she could be grossing we could be grossing you could be grossing they could be grossing
Perfect
I could have grossed you could have grossed she could have grossed we could have grossed you could have grossed they could have grossed
V-ing perfect
I could have been grossing you could have been grossing she could have been grossing we could have been grossing you could have been grossing they could have been grossing
Negation
Simple form
I could not gross you could not gross she could not gross we could not gross you could not gross they could not gross
V-ing form
I could not be grossing you could not be grossing she could not be grossing we could not be grossing you could not be grossing they could not be grossing
Perfect
I could not have grossed you could not have grossed she could not have grossed we could not have grossed you could not have grossed they could not have grossed
V-ing perfect
I could not have been grossing you could not have been grossing she could not have been grossing we could not have been grossing you could not have been grossing they could not have been grossing
Interrogative form
Simple form
could I gross? could you gross? could she gross? could we gross? could you gross? could they gross?
V-ing form
could I be grossing? could you be grossing? could she be grossing? could we be grossing? could you be grossing? could they be grossing?
Perfect
could I have grossed? could you have grossed? could she have grossed? could we have grossed? could you have grossed? could they have grossed?
V-ing perfect
could I have been grossing? could you have been grossing? could she have been grossing? could we have been grossing? could you have been grossing? could they have been grossing?
Interro-negative form
Simple form
could I not gross? could you not gross? could she not gross? could we not gross? could you not gross? could they not gross?
V-ing form
could I not be grossing? could you not be grossing? could she not be grossing? could we not be grossing? could you not be grossing? could they not be grossing?
Perfect
could I not have grossed? could you not have grossed? could she not have grossed? could we not have grossed? could you not have grossed? could they not have grossed?
V-ing perfect
could I not have been grossing? could you not have been grossing? could she not have been grossing? could we not have been grossing? could you not have been grossing? could they not have been grossing?