Rocks and soil
岩石和土壤
There are many different kinds of materials in the earth.
地球上有许多不同种类的物质。
Some materials are rough and others are smooth.
有些材料粗糙，有些材料光滑。
Granite is a kind of hard rock.
花岗岩是一种坚硬的岩石。
It is very strong and good to build things.
它非常坚固，非常适合建造东西。
We can make buildings with granite.
我们可以用花岗岩建造建筑。
Sand is a material that comes from rocks.
沙是一种来自岩石的物质。
Sand is very rough and there is a lot of it on a beach.
沙子很粗糙，海滩上有很多沙子。
Clay comes from soil.
粘土来自土壤。
It is sticky and soft, but becomes hard when it is dry.
它又粘又软，但干燥时会变硬。
Humus is pieces of dead plants and animals.
腐殖质是死去的植物和动物的碎片。
Humus comes from the top soil.
腐殖质来自表层土壤。
Sand clay and humus are kinds of soil.
砂土和腐殖质是土壤的种类。
Soil is the top layer of the earth.
土壤是地球的顶层。