with a massless rod and a bob at the end,

和一个物块做成一个单摆
the time it takes to finish an oscillation,

一次振荡的时间
in fact, will depend on the amplitude.

其实是依赖于振幅的
But only for small oscillations,

只有对小的振荡
when sin(θ) can be approximated by θ,

sin(θ) 近似等于 θ
you will find whether you do that oscillation, or that oscillation,

你才会发现这样振荡还是这样振荡
the time is the same.

所需的时间是相同的
But if you go too far,

但如果摆的太大
the other terms in sin(θ) will kick in,

sin(θ) 中的其它项就会有影响
and the result is no longer true.

结果就不对了
The period of a pendulum, in fact, is not just a function of l and g,

单摆的周期其实不仅仅是 l 和 g 的函数
but also a function of the amplitude.

也是振幅的函数