n sale不是固定搭配,意思是正在出售
eg.The new album of F.I.R is in sale now.
on sale
是超市里特价的标志.现在也用在很多店面的打折品里.原意是拍卖品待售品,现在基本上都用为打折的意思.
eg.Everything in wal-mart is on sale now.