The top layer of earth — the dark, soft, rich soil at the surface where plants put their roots and where almost all the food and life in the ground is. Dig down maybe fifteen to thirty centimetres and you pass through it; below it is subsoil, which is paler, harder and much poorer for growing things.

The top layer of earth地表最上面的一層土——the dark, soft, rich soil at the surface那種黑黑軟軟、養分豐富的表層土壤 where plants put their roots植物會把根扎在裡面 and而 where almost all the food and life in the ground is土裡幾乎所有的養分和生物也都在那裡。Dig down maybe fifteen to thirty centimetres往下挖大概十五到三十公分 and you pass through it你就會穿過這層土；below it它下面是 is subsoil心土，which is paler, harder and much poorer for growing things顏色比較淺、比較硬，也比較不適合種東西。

It is an uncountable noun, so you say "a lot of topsoil", "some topsoil", never "a topsoil" or "two topsoils".

It它 is是 an uncountable noun不可數名詞，so所以 you say你會說 "a lot of topsoil", "some topsoil""a lot of topsoil"、"some topsoil"這樣，never絕不會說 "a topsoil" or "two topsoils""a topsoil"或"two topsoils"。

You will meet it most in gardening ("I bought three bags of topsoil"), in farming, and in news about the environment, because topsoil takes hundreds of years for nature to make and can be washed or blown away in a single storm — that loss is called erosion, and it is one of the quiet big problems in the world.

You will meet it你最常會在 most in gardening園藝裡遇到它 ("I bought three bags of topsoil")（像"I bought three bags of topsoil"，我買了三袋表土），in farming在農業裡，and而且 in news about the environment在環境相關的新聞裡也會遇到，because因為 topsoil takes hundreds of years for nature to make表土要花大自然好幾百年才能形成，and而且 can be washed or blown away in a single storm一場暴風雨就可能把它沖走或吹走——that loss這種流失 is called erosion叫做侵蝕，and而且 it is one of the quiet big problems in the world是這個世界上一個不太顯眼、卻很嚴重的問題。

This is a plain everyday word for gardeners and a serious technical word for scientists at the same time, and it does not change its shape between the two.

This這個字 is是 a plain everyday word for gardeners對園丁來說是個平常的日常用字，and而 a serious technical word for scientists at the same time同時對科學家來說也是一個嚴肅的專業術語，and而且 it does not change its shape between the two它在這兩種用法裡形式都不會變。