Neck and neck这个表达出自于跑马。在赛马场上，马匹凭一个颈位之差取胜，叫做The horse wins by aneck。假如两匹马neck and neck，那就是“并驾齐驱”的意思了。
引伸开来，这个表达可以指在种种激烈的竞争中双方“势均力敌，旗鼓相当”。
For example:
A poll taken shortly before the election showed that the two presidential candidates are still neck and neck.
选举前不久的民意调查显示，两名总统候选人依然是势均力敌。
Neck and neck三字之间加上连字号，可作形容词用。
For example:
It was a neck-and-neck competition.
那是一场势均力敌的比赛。