RELATIONSHIP 的复数形式怎么用？

这个－ship，表示的是一种：关系，是那种抽象的关系，内在的关系。
是没有复数的哦

详细的看这里呵呵
http://zhidao.baidu.com/question/7682628.html?si=1

没有复数形式。它是抽象名词。中文“友谊”一词怎么用，英语也怎么用，没什么太多特别的用法。放心好了，楼主。

That's about the only guarantee when it comes to relationships.
What's the expression used to describe someone who is constantly in casual relationships with different people and doesn't want to settle down?