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