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Working With Clay: A How-to Guide (1/2)

Clay is found almost everywhere in the world. It is formed by the action of wind and water on rocks over thousands of years. The rocks change in both chemical and physical ways. Chemically, elements like potassium and aluminum are added and taken away. Physically, the rocks break down into smaller and smaller pieces. After a long time, some of the rock changes to clay.

Clay is important because it is used around the world to make containers of all kinds. Potters add water to soften the clay. This makes it easier to form into shapes by hand or by machine. Then it is fired in an extremely hot stove. The result is a container with a hard surface that will last for many years.

In many countries, clay was formed from volcanoes. This kind of clay usually contains many minerals. So the fires to make containers from volcanic" class="hjdict" word="volcanic" target=_blank>volcanic clay must be hotter than those used for non-volcanic clay. The fires may be as hot as 1400 degrees Celsius.

It is also important to dry the clay containers slowly. This means that the highest temperature should not be reached too fast.



关键字:英语听力
生词表:
  • aluminum [,ælju´miniəm, ,ælə´miniəm] 移动到这儿单词发声 n.铝 四级词汇
  • physically [´fizikəli] 移动到这儿单词发声 ad.按照自然规律 四级词汇
  • container [kən´teinə] 移动到这儿单词发声 n.容器;箱,匣 四级词汇
  • volcanic [vɔl´kænik] 移动到这儿单词发声 a.(象)火山的;爆发的 四级词汇


文章标签:VOA