I could blush you could blush she could blush we could blush you could blush they could blush
V-ing form
I could be blushing you could be blushing she could be blushing we could be blushing you could be blushing they could be blushing
Perfect
I could have blushed you could have blushed she could have blushed we could have blushed you could have blushed they could have blushed
V-ing perfect
I could have been blushing you could have been blushing she could have been blushing we could have been blushing you could have been blushing they could have been blushing
Negation
Simple form
I could not blush you could not blush she could not blush we could not blush you could not blush they could not blush
V-ing form
I could not be blushing you could not be blushing she could not be blushing we could not be blushing you could not be blushing they could not be blushing
Perfect
I could not have blushed you could not have blushed she could not have blushed we could not have blushed you could not have blushed they could not have blushed
V-ing perfect
I could not have been blushing you could not have been blushing she could not have been blushing we could not have been blushing you could not have been blushing they could not have been blushing
Interrogative form
Simple form
could I blush? could you blush? could she blush? could we blush? could you blush? could they blush?
V-ing form
could I be blushing? could you be blushing? could she be blushing? could we be blushing? could you be blushing? could they be blushing?
Perfect
could I have blushed? could you have blushed? could she have blushed? could we have blushed? could you have blushed? could they have blushed?
V-ing perfect
could I have been blushing? could you have been blushing? could she have been blushing? could we have been blushing? could you have been blushing? could they have been blushing?
Interro-negative form
Simple form
could I not blush? could you not blush? could she not blush? could we not blush? could you not blush? could they not blush?
V-ing form
could I not be blushing? could you not be blushing? could she not be blushing? could we not be blushing? could you not be blushing? could they not be blushing?
Perfect
could I not have blushed? could you not have blushed? could she not have blushed? could we not have blushed? could you not have blushed? could they not have blushed?
V-ing perfect
could I not have been blushing? could you not have been blushing? could she not have been blushing? could we not have been blushing? could you not have been blushing? could they not have been blushing?