应变硬化
参考答案：在屈服点以后（在塑性变形区），岩石（材料）的应力—应变曲线呈上升曲线，如要使之继续变形，需要相应地增加应力，这种现象称之为应变硬化。
根据句意提示补全单词。
1. May I use a ________ if I get lost in the forest.
2. The boy is going ________with his cousin if it is sunny tomorrow.
3. Riding on the roadway is not ________.
4. When you ride on the roadway, it is important to ________ the traffic rules.
5. You should walk your bike across the ________ and in school.
圆的周长是18.84厘米，那么半圆的周长是______分米．
