£1/$20/30% off
注意：off前面的数字或百分比表示减去的那部分金额，并非折后的价格，比如30% off即是说一件商品降30%的价，就是我们常说的“打七折”，而不是“打三折”。
30% off all computers in the summer sales
We got $10 off the chair.
30% off 还可以用 30% discount
There’s a 30% discount on all goods.
买一送一
Buy one get one freetwo for the price of oneon sale/in the sales: 正在打折
on sale 美式英语的说法in the sales 英式英语的说法I got the coat on sale in Macy's. It only cost $45.
His suit was bought in the sales for £100.
be reduced: 减价
The CDs were reduced from $10 to $5.
special offer特价促销
They’ve got a special offer for children.