买一送一的英文：
buy one get one free

参考例句：

"This is a good deal: Buy 1 , get 1 free."
这可是个好买卖:买一送一

As a matter of fact, the salesmanship of "two for one" is a good way of advertising.
买一送一的推销术，实际上是一种不错的广告。

2 lether shoes purchased for the price of one
买一送一(买两双皮鞋只须付一双价钱)

During the small commodities sales exhiBition, customers who Buy one item will get another similar item free.
小商品展销期间，买一送一，买啥送啥。

buy是什么意思：
n. 所购的物品；便宜货；买卖
v. 买；获得；购得；收买；相信

Buying bonds is safer than buying stocks.
买债券比买股票风险小。

It's a good buy at that price.
这是一笔价钱合算的买卖。

That shirt was a really great buy.
这个衬衫真是便宜货。

one是什么意思：
num. 一；同一个、最重要的一个
det. 代替a或an，表示强调；某位（用于不太熟悉之人的姓名之前）
pron. 任何人；一个人；一个事物；其中的一个人

One, Taipei, one way.
台北单程票一张。

This one is not a spoof.
这个就不是开玩笑了。

One and one make(s) two.
一加一等于二。

get是什么意思：
v. 得到；抓住；获得；受到（惩罚）；说服；到达，来；变得，变成；设法；开始
n. 幼兽；生殖

Get to the bottom of
弄个水落石出

Saving is getting
节约等于收入

It was getting dark.
天色渐暗。