Act of buying or selling.

买卖；交易。

Thing bought at a market.

(购于市场的)商品。

All the activities involved in the advertising, display, selling, shipping, storing, etc. of a product.

销售行为(包括商品之广告、展示、出售、运送、储存等活动)。

Theory and practice of (large-scale) selling.

市场学。