buy为什么不双写

　　例句：

　　We're buying a new TV with the money.

　　我们要用这笔钱买一台新电视机。

　　I want to buy a present for my mother and father.

　　我想给爸爸妈妈买件礼物。

　　It would be more economical to buy the bigger size.

　　买尺寸大点的更实惠。

　　We make sure our clients get the best that money can buy.

　　我们确保客户买到最好的产品。

　　We need to buy some new furniture.

　　我们需要买一些新家具。