I could trade you could trade she could trade we could trade you could trade they could trade
V-ing form
I could be trading you could be trading she could be trading we could be trading you could be trading they could be trading
Perfect
I could have traded you could have traded she could have traded we could have traded you could have traded they could have traded
V-ing perfect
I could have been trading you could have been trading she could have been trading we could have been trading you could have been trading they could have been trading
Negation
Simple form
I couldn't trade you couldn't trade she couldn't trade we couldn't trade you couldn't trade they couldn't trade
V-ing form
I couldn't be trading you couldn't be trading she couldn't be trading we couldn't be trading you couldn't be trading they couldn't be trading
Perfect
I couldn't have traded you couldn't have traded she couldn't have traded we couldn't have traded you couldn't have traded they couldn't have traded
V-ing perfect
I couldn't have been trading you couldn't have been trading she couldn't have been trading we couldn't have been trading you couldn't have been trading they couldn't have been trading
Interrogative form
Simple form
could I trade? could you trade? could she trade? could we trade? could you trade? could they trade?
V-ing form
could I be trading? could you be trading? could she be trading? could we be trading? could you be trading? could they be trading?
Perfect
could I have traded? could you have traded? could she have traded? could we have traded? could you have traded? could they have traded?
V-ing perfect
could I have been trading? could you have been trading? could she have been trading? could we have been trading? could you have been trading? could they have been trading?
Interro-negative form
Simple form
couldn't I trade? couldn't you trade? couldn't she trade? couldn't we trade? couldn't you trade? couldn't they trade?
V-ing form
couldn't I be trading? couldn't you be trading? couldn't she be trading? couldn't we be trading? couldn't you be trading? couldn't they be trading?
Perfect
couldn't I have traded? couldn't you have traded? couldn't she have traded? couldn't we have traded? couldn't you have traded? couldn't they have traded?
V-ing perfect
couldn't I have been trading? couldn't you have been trading? couldn't she have been trading? couldn't we have been trading? couldn't you have been trading? couldn't they have been trading?