commerce 多指大規模的買賣或易貨關系。
trade 普通用詞，含義廣。既可指某種具體的商業又可指廣泛的貿易。
bargain 多指買賣雙方通過談判、協商就商品質量、數量、價格等項達成協議所成的生意。
deal 口語用詞，指買賣雙方經過交涉達成協議成交。
bargain的例句：
1. They prefer to bargain with individual clients, for cash.
在現款方面，他們更愿意同散戶打交道。
2. They need hostages in order to bargain with the government.
他們要想同政府討價還價就得有人質。
3. Fresh salmon is a bargain at the supermarket this week.
這周超市的新鮮鮭魚特價銷售。
4. Clothes are the best bargain, with many items marked down.
買衣服是最劃算的，許多衣服都降價了。
5. Majorca and Ibiza are tops for holiday bargain-hunters in June.
對于實惠型度假者來說，馬略卡島與伊維薩島是6月份的絕好選擇。
6. "It's a fabulous deal, a real bargain."
“這樁買賣真讓人難以置信，絕對合算。”
7. At this price the wine is a bargain.
這種葡萄酒賣這個價真是很便宜。
8. More and more criminals will agree to plea-bargain.
越來越多的罪犯會同意接受認罪辯訴協議。
9. The so-called bargain was just a big con!
這種所謂的減價商品只不過是個大騙局!
10. The bargain prices are expected to entice customers away from other stores.
低廉的價格意在把顧客從其他商店吸引過來。
11. You can drive a hard bargain in the free market.
在自由市場上你可使勁地討價還價。
12. The women in the market often bargain away for hours.
女人們經常在市場里一連幾小時討價還價。
13. Don't bargain on getting any support from her; she's very selfish.
別指望從她那里得到什么援助, 她很自私。
14. We do not like to bargain with you about the prices.
我們不想就價格問題與你討價還價。
15. This shirt was a bargain — only ￡15 in a sale.
這件襯衫是便宜貨,大減價時只賣十五英鎊。