What is the main ingredient in chalkboard chalk?

粉笔的主要成分是什么？

Compare that to a black chalkboard, which is pretty dark.

拿一块黑板作比较，我们都知道黑板的颜色已经很深了。

She hates the sound of nails scratching on a chalkboard.

她讨厌指甲刮黑板的声音。

I have this chalkboard to-do list at home but only because I'm old school.

我家里有这么一块黑板，上面写着待办事项清单，但这只是因为我是个老古板。

Its surface is actually pretty dark, with about the same reflectivity as a chalkboard or asphalt.

它的表面其实非常暗淡，只有大约相当于黑板或者沥青的反射率。

Ten minutes down the road from Mariama Daffe's home, women write on a chalkboard at the local elementary school.

从马里亚玛·达菲家出来走路10分钟，有一所当地小学，妇女们在黑板上写字。

It's so aggravating when people scratch a chalkboard with their nails.

当人们用指甲刮黑板时，情况会变得非常糟糕。

I also put an advanced Fourier system on the main hallway chalkboard.

走廊黑板上有高级傅立叶算式。

I mostly have whiteboards now and very, very few chalkboards because this sound is so aggravating.

我现在主要有白板， 黑板非常非常少，因为这种声音太烦人了。

But do not alter anything on the chalkboard.

但是不要改动黑板上写的东西。