I could jump you could jump he could jump we could jump you could jump they could jump
V-ing form
I could be jumping you could be jumping he could be jumping we could be jumping you could be jumping they could be jumping
Perfect
I could have jumped you could have jumped he could have jumped we could have jumped you could have jumped they could have jumped
V-ing perfect
I could have been jumping you could have been jumping he could have been jumping we could have been jumping you could have been jumping they could have been jumping
Negation
Simple form
I could not jump you could not jump he could not jump we could not jump you could not jump they could not jump
V-ing form
I could not be jumping you could not be jumping he could not be jumping we could not be jumping you could not be jumping they could not be jumping
Perfect
I could not have jumped you could not have jumped he could not have jumped we could not have jumped you could not have jumped they could not have jumped
V-ing perfect
I could not have been jumping you could not have been jumping he could not have been jumping we could not have been jumping you could not have been jumping they could not have been jumping
Interrogative form
Simple form
could I jump? could you jump? could he jump? could we jump? could you jump? could they jump?
V-ing form
could I be jumping? could you be jumping? could he be jumping? could we be jumping? could you be jumping? could they be jumping?
Perfect
could I have jumped? could you have jumped? could he have jumped? could we have jumped? could you have jumped? could they have jumped?
V-ing perfect
could I have been jumping? could you have been jumping? could he have been jumping? could we have been jumping? could you have been jumping? could they have been jumping?
Interro-negative form
Simple form
could I not jump? could you not jump? could he not jump? could we not jump? could you not jump? could they not jump?
V-ing form
could I not be jumping? could you not be jumping? could he not be jumping? could we not be jumping? could you not be jumping? could they not be jumping?
Perfect
could I not have jumped? could you not have jumped? could he not have jumped? could we not have jumped? could you not have jumped? could they not have jumped?
V-ing perfect
could I not have been jumping? could you not have been jumping? could he not have been jumping? could we not have been jumping? could you not have been jumping? could they not have been jumping?