trade/ treɪd /

1.noun [u] 
(buying and selling) 贸易

2.noun [c] 
(skill,job) 谋生之道

3.noun [c] 
(specific kind of work) 行业

the book trade
图书业
4.vi.
(do business) 做生意

5.vt.[esp US] 
to trade sth (for sth) (exchange) 用某物交换(某物)

to trade with
 [+country,company] 与…进行贸易
to trade in
 [+merchandise] 从业于