導購口語:

Prices have up to twenty percent off. Do not miss the chance.
8折優惠，不要錯過機會。
We give you a discount of 20% since we're renewing our inventory.
我們因為在出清存貨，所以商品八折出售。
Opening sales at preferential prices, all goods 20% off.
開張大酬賓，所有商品八折優惠。

語句解析:

give sb. a discount=offer sb. a discount （主語）給某人打折扣。
give sb. a discount of 20% 給予某人八折優惠，也可以說give sb. a 20% discount。Give sb. a discount on sth. 給予某人某物的折扣。

情景再現:

The mall is giving a 20% discount on some brand-name clothes.
商場正在進行名牌服裝八折優惠活動。
Since you are our regular customer, I could make a concession.
由于你是我們的熟客，我可以給你優惠。