The ozone layer surrounds the Earth roughly 25km above us. Many human activities are thinning the layer.

臭氧层在地球表层上空大约25km的位置。许多人类活动正削薄臭氧层。

Her hair had been thinned and cut shorter.

【thin】她的头发削薄了，剪短了。

Now you can see, here Ive selected a piece of flint which is relatively long and thin - not a great deal of work to thin it down.

“现在你瞧瞧，这儿呢，我挑了块燧石，比较细长的，要削薄下来工作量并不大。”

And what we would do then, is actually thin the piece down and refine the shape, work our way round ... and in about 10 to 15 minutes, theres your handaxe.

接下来我们就把这里细细削薄，沿着边缘一圈削下来… … 这样加工上大概十到十五分钟，你的手斧就出来了。”