你能把那支铅笔递给我吗？

Can you pass me that pencil?

那支铅笔与这支铅笔一样长。

That pencil is as long as this one.

这支铅笔是那支铅笔长度的一半。

This pencil is half as long as that one.

把课桌上的那支铅笔拿走。

Take away the pencil which is lying on the desk.

这就是我昨天用的那支铅笔。

This is the same pencil that I used yesterday.

我带在背包里的那支铅笔是“永利”牌镀银带可推动的铅笔头的，它是我母亲去世后留在她的抽屉里的。

The pencil I carry in my back-back is a silver-plated Eversharp with propelling leads, which my mother left in her drawer when she died.

好的，把那支铅笔放在上面。好啦！好，现在该玩了。来吧！

Ok, put that pencil up here. Finished! Ok, now it's time to play. Come on!

发现光有波的属性之后，自然而然地就能解释颜色是什么，以及那支铅笔怎么会是黄色的。

And, as a bonus, understanding that light acts like a wave leads naturally to an explanation of what color is and why that pencil looks yellow.