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Lesson21 A piece of slate
第21课 一块石板
Look at your slate, and see what it is made of. It is a very thin, smooth, grey stone. The pencil with which you write upon it is also a piece of soft slate.
小朋友, 看看你自己写字用的石板, 了解一下它是什么做的? 这是一块非常薄、非常光滑的灰色石头。你在板石上写字的笔, 也是一块比较软的石头, 叫做板石。
When you rub the soft slate-pencil upon the slate, many little pieces of the pencil are broken off. These tiny pieces form the white marks which you see when you write. They do not stick to the slate, but can easily be rubbed off with a wet sponge.
把软的板石笔在板石上蹭蹭, 就会有很多板石笔的碎片掉下来。这些碎片就变成了你写字的时候看见的白印子。这些白印子不是黏在板石上的, 用湿海绵很容易就能擦掉。
The slate is not at all like the lump of putty which we made. The putty was soft; we could press it into any shape we pleased. But the slate is hard. However much we squeeze it, we cannot change its shape.
板石, 跟我们以前做过的腻子块儿, 一点也不像。腻子是很软的, 我们想要什么形状, 就可以把它捏成什么形状。可是板石很硬, 不管怎么使劲儿地挤, 都不能改变它的形状。
The putty did not break when it fell to the ground; but if we drop a slate, it will break. So we say that the slate is brittle; it snaps or breaks easily.
腻子块儿掉在地上是不会碎的, 可要是把一块板石掉到地上就会摔碎。所以我们说, 板石很“脆”, 很容易就能折断、打碎。脆的英语叫brittle.
Like all solids, slate keeps its shape, and it keeps its size too. You cannot change a little slate into a big one, however hard you pull at it to try to stretch it.
跟所有的固体一样, 板石有固定的形状, 也有固定的大小。不管怎么拉它, 拽它, 都不能把一块小板石变成一块大板石。
Pieces of slate are put on the roofs of houses, to keep out the rain. Water cannot pass through slate. The slater makes two little holes in each slate, and then nails them on to the roof.
板石片也放在屋顶上, 用来挡雨。水是透不过板石的。装板石的工人在每一块板石上钻出两个洞, 用钉子把板石固定在屋顶上。
But where do slates come from? If you ever go to Wales, or to Cornwall, or to Scotland, you may see great holes in the hill-sides—"quarries, " the men call them—where all the rock or stone is nothing but slate. A SLATE QUABRY（板石的采石场）
板石是怎么来的呢? 如果你去一趟威尔士、康沃尔郡, 或者苏格兰, 你可能会在山坡上看见一些大洞, 人们管这种大洞叫“采石场”, 英语叫quarry. 在这些地方, 所有的石头全是板石。
Some men break off great lumps of the rock, and then other men split these lumps into the thin pieces we call slates. We can tell slate from all other rocks by the way it splits into very thin layers.
一些人把板石块开采出来, 然后另一些人, 把这些大石块分成我们叫“板石”的细片。板石跟其他石头的不同, 就在于它能分成非常薄的石片。
Scrape some slate-pencil into a glass of water. The water looks muddy. The slate itself was once mud at the bottom of the sea. That was a very long time ago; and the slate has been so squeezed and heated inside the earth since then, that it has become hard and stony.
把板石笔擦一些碎屑下来, 让碎屑落进一杯水里, 水看上去就成了泥浆。很久很久以前, 板石就曾经是海底的泥, 后来在地球内部被挤压、加热, 最后变成了硬硬的石头。
We often find pieces of slate like the one in the picture, full of marks of the shells or of the fishes that lived in the sea long ago. When these creatures died, they sank to the bottom, and were buried in the mud.
我们经常会找到这张图上这样的石头, 上面有很多远古生活在海里的贝壳或者鱼类的印迹。这些动物是在死掉之后, 沉到海底, 被埋在泥中的。
