对材料施加应力并在释放应力后不导致变形的最大单位应力称为（）。
A、材料的弹性介质
B、材料的泊松比
C、材料的杨氏模量
D、材料的弹性极限
参考答案：D
If a motorist had driven 1 hour longer on a certain day and at an average rate of 5 miles per hour faster, he would have covered 70 more miles than he actually did. How many more miles would he have covered than he actually did if he had driven 2 hours longer and at an average rate of 10 miles per hour faster on that day ？（）
A．100
B．120
C．140
D．150
E．160
