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