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成才之路 英语,路漫漫其修远兮 吾将上下而求索,外研版 必修1,A Lesson in a Lab,Module 5,你做过实验吗？你知道化学变化与物理变化的不同吗？让我们一同走进属于我们自己的实验室吧。 There are two kinds of changesthe chemical change and the physical change. In a chemical change, there is a new substance formed. Breaking up water into hydrogen(氢气)and oxygen is a chemical change. In each of the chemical changes, at least one new substance is formed. A change is not a chemical change if it doesnt form a new substance.,Physical changes are very common, too. There are many examples. You can make a physical change by tearing a piece of paper into two, or by cutting a piece of iron with a lathe(车床). Here paper is still paper, and the iron is still iron.,Another way of making physical change is dissolving something in water. When you dissolve salt in water, the salt disappears, You may think that a new substance has been formed. But really there is no new substance. The salt is still salt. You can still taste it. So the dissolving of anything is a physical change. When water freezes, the change is also a physical one. The water changes from a liquid to a solid. But it is still the same substance. That is why the freezing of anything is a physical change.,1.substance n. 物质 2break up 分解 3dissolve v. 溶解,
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