Not all materials produce stress-strain diagrams on which there is a clear indication of the start of yielding as the load is increased.
不是所有的材料都会产生应力-应变图，即当载荷增加时显现出开始屈服的迹象。
2
This is an indication that some young couples may opt to remain childless as they are worried about problems such as financial strain, nurturing and education.