I can trade you can trade he can trade we can trade you can trade they can trade
V-ing form
I can be trading you can be trading he can be trading we can be trading you can be trading they can be trading
Perfect
I can have traded you can have traded he can have traded we can have traded you can have traded they can have traded
V-ing perfect
I can have been trading you can have been trading he can have been trading we can have been trading you can have been trading they can have been trading
Negation
Simple form
I cannot trade you cannot trade he cannot trade we cannot trade you cannot trade they cannot trade
V-ing form
I cannot be trading you cannot be trading he cannot be trading we cannot be trading you cannot be trading they cannot be trading
Perfect
I cannot have traded you cannot have traded he cannot have traded we cannot have traded you cannot have traded they cannot have traded
V-ing perfect
I cannot have been trading you cannot have been trading he cannot have been trading we cannot have been trading you cannot have been trading they cannot have been trading
Interrogative form
Simple form
can I trade? can you trade? can he trade? can we trade? can you trade? can they trade?
V-ing form
can I be trading? can you be trading? can he be trading? can we be trading? can you be trading? can they be trading?
Perfect
can I have traded? can you have traded? can he have traded? can we have traded? can you have traded? can they have traded?
V-ing perfect
can I have been trading? can you have been trading? can he have been trading? can we have been trading? can you have been trading? can they have been trading?
Interro-negative form
Simple form
can I not trade? can you not trade? can he not trade? can we not trade? can you not trade? can they not trade?
V-ing form
can I not be trading? can you not be trading? can he not be trading? can we not be trading? can you not be trading? can they not be trading?
Perfect
can I not have traded? can you not have traded? can he not have traded? can we not have traded? can you not have traded? can they not have traded?
V-ing perfect
can I not have been trading? can you not have been trading? can he not have been trading? can we not have been trading? can you not have been trading? can they not have been trading?