传统的教科书、死板的老学究却是认为只能选among，但是语言的使用是否符合规范不是由“规定”控制。
学语言的人应该记住这句话：使用就是规则。
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保守死板的规定是：between只能用在指两这者之间，超出2个以上的情况下只能使用among.但是实际情况并不是这么简单。如果你想表达的（包括你心里的表达的过程和顺序）是一对一的关系（其实我们不可能同时将2着以上的东西进行对比，正如我们不可能绝对同时和2个以上的人说话一样），我们就完全可以在表达2这以上的概念时使用between.
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在一般情况下，between表示“两者之间”，among表示“三者或三者以上的人或物之间（或者说是一个物体位于一组彼此不可分离的物体之间）”。请看下面的例句：
1）The train runs between Beijing and Shanghai．这辆火车运行于北京和上海之间。
2）I'm sure（that）he will come back from Tonghua between 2 and 3 o'clock．我敢肯定，他会在2点到3点之间从通化回来。
3）This village lies among the mountains．这个村庄位于群山之间。
4）Pass it among the students of Class Six，Grade Two．让这件事情在二年级（6）班流传。
但在下面的几种情况下，among却消失得无影无踪，让between占了上风。
1）后面虽然接的是三个或三个以上的名词，但是我们应该把这些物体分别看待，实际上强调的是“二者之间”。例如：
①Lily was badly ill．The doctor told her to take medicine between three meals every day．莉莉病得很厉害，大夫告诉她应在三餐之间吃药。
②There is a pear tree between the apple trees．在（许多）苹果树之间，有一棵梨树。
③A big river runs between high mountains．一条大河在高山之间流淌。
2）当两个以上的人或者物由and连接时，也用between连接。例如：
①Dr Li sits between you，me and him．李博士就坐在我、你和他之间。
②When we talk about the universe，we mean the earth，the sun，the moon and the stars and the space between them．当我们谈论到宇宙时，我们的意思就是指地球、太阳、月亮、星星以及他们之间的空间。
3）在一般情况下，the difference与between连用。例如：
—What is the difference between the three of them？
—I'm sorry I have no idea．
———他们三者之间的不同点是什么？———很抱歉，我不知道。
4）在表示疆界、边界或国际关系时，也用between。例如：
①Switzerland lies between France，Italy，Austria and Germany．瑞士位于法国、意大利、奥地利和德国之间。
②A treaty was concluded between the three nations．三个国家签订了一个条约。
③Agreements were made between the different countries．各国之间都达成了协议。
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英语解释：
It is often argued that between should be used to express a relationship involving two of something, and among should express relationships involving three or more, but in fact that generalization does not describe the way English has long used these prepositions. Between can be used of as many items as you like if the relationship is one-to-one, however much it may be repeated with different partners: Economic relations between Great Britain, France, and Italy [or between some members of the EEC] are tense at present. Among works with any plural number above two: Among the milling ballplayers, fans, and reporters were the four umpires. Best advice: use between of two and among of three or more in Edited English, but elsewhere, and especially at lower levels, feel free to use between of two, three, or more. But see also AMONG.
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