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 couldn't jump you couldn't jump he couldn't jump we couldn't jump you couldn't jump they couldn't jump
V-ing form
I couldn't be jumping you couldn't be jumping he couldn't be jumping we couldn't be jumping you couldn't be jumping they couldn't be jumping
Perfect
I couldn't have jumped you couldn't have jumped he couldn't have jumped we couldn't have jumped you couldn't have jumped they couldn't have jumped
V-ing perfect
I couldn't have been jumping you couldn't have been jumping he couldn't have been jumping we couldn't have been jumping you couldn't have been jumping they couldn't 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
couldn't I jump? couldn't you jump? couldn't he jump? couldn't we jump? couldn't you jump? couldn't they jump?
V-ing form
couldn't I be jumping? couldn't you be jumping? couldn't he be jumping? couldn't we be jumping? couldn't you be jumping? couldn't they be jumping?
Perfect
couldn't I have jumped? couldn't you have jumped? couldn't he have jumped? couldn't we have jumped? couldn't you have jumped? couldn't they have jumped?
V-ing perfect
couldn't I have been jumping? couldn't you have been jumping? couldn't he have been jumping? couldn't we have been jumping? couldn't you have been jumping? couldn't they have been jumping?