用介词in,例如:1、Richard refused to trade in his old Canon cameras.理查德拒绝用他的旧佳能相机以旧换新。2、They do a lively trade in souvenirs and gifts.他们做纪念品和礼品生意,做得有声有色。3、The illegal trade in animal products continues to flourish.野生动物制品的非法交易仍旧猖獗。