VOA慢速英语2009年-Development Report - Working With Clay: A
时间：2019-01-11 作者：英语课 分类：VOA慢速英语2009年（九）月
This is the VOA Special English Development Report.
Clay
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 1 are added and taken away. Physically 2, 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 3 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 4. This kind of clay usually contains many minerals. So the fires to make containers from volcanic 5 clay must be hotter than those used for non-volcanic clay. The fires may be as hot as one thousand four hundred degrees Celsius 6.
It is also important to dry the clay containers slowly. This means that the highest temperature should not be reached too fast.
You can add materials to clay to gain desired results. For example, you can add sand to prevent tiny breaks or lines from forming in the finished product. But you should not use sand from the coasts of oceans. Instead, you should use sand from rivers or from other areas of land that are not near the sea.
You can usually find good clay in low areas of islands or land, especially if volcanoes helped form the land. Clay often exists in fields covered with some water. The clay will be found about one meter below the ground. River banks often also have clay about one meter or less under the surface.
You can recognize clay because it is very shiny when it is wet. You can also perform a test. Take some of the material and add enough water to it to make it seem like you are making bread. Then press it in your hand until it is about the size of an egg. It is probably clay if it holds together instead of falling apart when you stop pressing.
And that's the VOA Special English Development Report, written by Gary Garriott. Guides to working with clay and other materials can be found on the EnterpriseWorks/VITA list of publications 7. These publications can be ordered for a charge. The list is available at enterpriseworks.org. Transcripts 8, MP3 and archives of our reports are at voaspecialenglish.com. I'm Chris Cruise 9.
- The aluminum sheets cannot be too much thicker than 0.04 inches.铝板厚度不能超过0.04英寸。
- During the launch phase,it would ride in a protective aluminum shell.在发射阶段，它盛在一只保护的铝壳里。
- He was out of sorts physically,as well as disordered mentally.他浑身不舒服，心绪也很乱。
- Every time I think about it I feel physically sick.一想起那件事我就感到极恶心。
- Plastics will soften when exposed to heat.塑料适当加热就可以软化。
- This special cream will help to soften up our skin.这种特殊的护肤霜有助于使皮肤变得柔软。
- Volcanoes and geysers erupt. 火山和间歇喷泉均能喷发。 来自《简明英汉词典》
- He has been able to tell us more about active volcanoes than any man alive. 他现在比任何人都能更多地向我们讲述有关活火山的情况。 来自《用法词典》
- There have been several volcanic eruptions this year.今年火山爆发了好几次。
- Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。
- The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
- The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。
- The related publications are far too numerous to list individually. 相关出版物太多，没法一一列举。 来自《简明英汉词典》
- A detailed list of our publications is available on request. 我们的出版物有一份详细的目录备索。 来自《简明英汉词典》
- Like mRNA, both tRNA and rRNA are transcripts of chromosomal DNA. tRNA及rRNA同mRNA一样，都是染色体DNA的转录产物。 来自辞典例句
- You can't take the transfer students'exam without your transcripts. 没有成绩证明书，你就不能参加转学考试。 来自辞典例句