函数地作用是：返回子字符串可以。

The substr function returns a part of a string.

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您可以使用此函数轻松地在PHP代码中创建实例声明。

This function allows you to easily create instance declarations from within your PHP code.

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spotLight 函数可以更多地控制聚光灯。

The spotLight function adds a spotlight with considerable controls.

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We started talking about these on Wednesday, and what we're going to start with is considering specifically the wave functions for multi-electron atoms.

我们从周三开始讨论这些，而且我们将要以特别地考虑,多电子原子的波函数,为开始。

麻省理工公开课 - 化学原理课程节选

Because in "Pay it Forward", they capture this very idea of human networks as exponential functions.

电影“让爱传出去，深刻地描述了,人类网络是指数函数的观点。

哈佛公开课 - 幸福课课程节选

So A gets 1, B gets 2, now the swap function itself starts executing line by line; so I declare a chunk of memory called temp.

所以A等于1，B等于2，现在swap函数自己开始,一行一行地执行，所以我声明了,叫做temp的一块内存。

哈佛公开课 - 计算机科学课程节选