I could four-flush you could four-flush he could four-flush we could four-flush you could four-flush they could four-flush
V-ing form
I could be four-flushing you could be four-flushing he could be four-flushing we could be four-flushing you could be four-flushing they could be four-flushing
Perfect
I could have four-flushed you could have four-flushed he could have four-flushed we could have four-flushed you could have four-flushed they could have four-flushed
V-ing perfect
I could have been four-flushing you could have been four-flushing he could have been four-flushing we could have been four-flushing you could have been four-flushing they could have been four-flushing
Negation
Simple form
I couldn't four-flush you couldn't four-flush he couldn't four-flush we couldn't four-flush you couldn't four-flush they couldn't four-flush
V-ing form
I couldn't be four-flushing you couldn't be four-flushing he couldn't be four-flushing we couldn't be four-flushing you couldn't be four-flushing they couldn't be four-flushing
Perfect
I couldn't have four-flushed you couldn't have four-flushed he couldn't have four-flushed we couldn't have four-flushed you couldn't have four-flushed they couldn't have four-flushed
V-ing perfect
I couldn't have been four-flushing you couldn't have been four-flushing he couldn't have been four-flushing we couldn't have been four-flushing you couldn't have been four-flushing they couldn't have been four-flushing
Interrogative form
Simple form
could I four-flush? could you four-flush? could he four-flush? could we four-flush? could you four-flush? could they four-flush?
V-ing form
could I be four-flushing? could you be four-flushing? could he be four-flushing? could we be four-flushing? could you be four-flushing? could they be four-flushing?
Perfect
could I have four-flushed? could you have four-flushed? could he have four-flushed? could we have four-flushed? could you have four-flushed? could they have four-flushed?
V-ing perfect
could I have been four-flushing? could you have been four-flushing? could he have been four-flushing? could we have been four-flushing? could you have been four-flushing? could they have been four-flushing?
Interro-negative form
Simple form
couldn't I four-flush? couldn't you four-flush? couldn't he four-flush? couldn't we four-flush? couldn't you four-flush? couldn't they four-flush?
V-ing form
couldn't I be four-flushing? couldn't you be four-flushing? couldn't he be four-flushing? couldn't we be four-flushing? couldn't you be four-flushing? couldn't they be four-flushing?
Perfect
couldn't I have four-flushed? couldn't you have four-flushed? couldn't he have four-flushed? couldn't we have four-flushed? couldn't you have four-flushed? couldn't they have four-flushed?
V-ing perfect
couldn't I have been four-flushing? couldn't you have been four-flushing? couldn't he have been four-flushing? couldn't we have been four-flushing? couldn't you have been four-flushing? couldn't they have been four-flushing?