朗文3L看听学英语第四册 Lesson 47

　　Lesson 47 Television Day: The sea
TV Commentary¹:
If you looked at the Pacific from a space-capsule you might think that the world was all water. You would hardly be able to see any land at all. Water covers most of the earth's surface.
The sea contains a large number of substances, besides common salt. If you boiled away some sea-water, you would find over forty different materials. For instance², out of a cubic mile of water you would get ninety-four tons of silver and three tons of gold! If it were possible to do this, it still wouldn't be worth the trouble. It would cost more to obtain these precious metals than they are worth. But the sea provides us with a great many materials which we can obtain easily and which we use a lot. For instance, we use huge quantities of sand in industry to make glass, detergents³ and cement⁴.
Besides materials like salt and sand, we obtain a great deal of food from the sea. One day we may even have undersea farms. We have hardly begun to explore the sea. In some ways it is less familiar than outer space.

1 commentary   

n.评论，评注；实况广播报导，现场口头评述

参考例句：

• He is giving the commentary on the basketball game.他正在对篮球赛作评论。
• His running commentary on the football match was excellent.他对这次足球赛所作的实况报道十分精彩。

2 instance   

n.例，例证，实例

参考例句：

• Can you quote me a recent instance?你能给我举一个最近的例子吗？
• He's a greedy boy,yesterday,for instance,he ate all our biscuits!他是个贪吃的孩子――比如，他昨天把我们的饼干都吃了！

3 detergents   

n.洗涤剂( detergent的名词复数 )

参考例句：

• Such detergents do not yellow the wool as alkali tends to do. 这种洗涤剂不会象碱那样使羊毛发黄。 来自辞典例句
• Development of detergents has required optimization of the surfactants structure. 发展洗涤剂时，要求使用最恰当的表面活性剂结构。 来自辞典例句

4 cement   

n.水泥；胶结材料；vt.粘结；巩固

参考例句：

• We need 100 tons of cement at most for this project.这项工程满打满算有一百吨水泥就足够了。
• Let's cement the parts together.咱们来把这些部件粘接在一起吧。