So close that the advantage or lead shifts from one to the other or is virtually indistinguishable. The term comes from horse racing¹, where the necks of two horses in competition appear to be side by side

eg: The two are neck and neck in developing a new operating system for the computer

Neck and neck的意思是二者十分相近，不分上下。最初源于赛马，形容两匹马并驾齐驱不分前后。

例：二人都在开发新电脑操作软件，不相伯仲.