摘要：
Annealingisawayofmakingmetalsofterbyheatingita ndthenlettingitcoolveryslowly.Ifmetalisheat... Annealing is a way of making metal softer by heating it and then letting it cool very slowly. If metal is heated and then cooled very quickly, for
example by dipping (浸) it in water, it will be very hard but also very brittle-that is, it will break easily. Metal that has been annealed is soft but does not break as easily. It is possible to make metal as hard or as soft as it is wished, by annealing it. The metal is heated, and allowed to cool slowly for a certain length of time. The longer the heated metal takes to cool slowly, the softer it becomes. Annealing can also be used on other material, such as glass.
1. Why do people put hot metal in water?
A. To make it hard. B. To make it soft.
C. To make it cool. D. To make it brittle.
2. In annealing, the required hardness of metal depends on __.
A. the quantity of water used B. the temperature of the metal
C. the softness of the metal D. the timing of the operation
3. As suggested by the text, how can glass be made less brittle?
A. It can be
heated and then cooled quickly.
B. It can be cooled and then heated slowly.
C. It can be heated and then cooled slowly.
D. It can be cooled and then heated quickly.
1、 答案为A,此题属推断归纳题.文中第二句说如果把金属加热,然后迅速放到水里冷却,也就会变得非常硬,但也变得脆.hard 是工艺的主观目的.brittle是伴随的客观结果,故选A而不选D.B项明显错误;C项是手段不是目的,因此,都可排除.
2、 答案为D,此题属概括归纳题.timing 是时间的选择.本答案的依据是5和6两句,"The metal is heated,…length of time.","The longer…the softer it becomes."cool 的时间是可以控制的,时间越长越 soft,即硬度就越低.由此我们可得出结论:在退火过程中,金属的硬度是受到冷却的时间长短影响的.
