for sale的意思是“待售”“供出售”,即“用于出售”。on sale有两个意思:一是表示“出售”,与for sale不同,它表示的是“进入销售环节”“处于被销售的状态”。二是表示“廉价出售”“打折出售”。

on sale

一是表示“出售”,与for sale不同,它表示的是“进入销售环节”“处于被销售的状态”。如:
(1)Tickets are on sale from the booking office. 售票处正在售票。
(2)This week's edition is on sale now at your local newsagents. 本期周刊已公开发售,读者可向各报贩购买。
(3)The new stamps are now on sale at main post offices. 新邮票现在各大邮局有售。
二是表示“廉价出售”“打折出售”。如:
(1)Bedding usually goes on sale in January. 床上用品通常在一月份降价出售。
(2)He was looking for a TV and found one on sale. 他正想买电视机,结果找到了一台特价的。
(3)All video equipment is on sale today and tomorrow. 今明两天所有录像设备降价销售。

for sale

for sale的意思是“待售”“供出售”,即“用于出售”。如:
(1)That chair is not for sale. 那把椅子是非卖品。
(2)I'm sorry,it's not for sale. 抱歉,这个不卖。
(3)We don't want our car anymore,it is for sale. 我们的汽车不想要了,供出售。