受外力作用的弹性直杆中，应力波传播速度与质点振动速度是有区别的，质点振动速度取决于（），而波速传播速度仅为材料性质的（）。
参考答案：应力大小；函数
Which of the following sentences is an opinion?
A．Four people in Jiangsu died in early April because of H7N9 bird flu infections.
B．China’s star swimmer Sun Yang won the first prize on April 1st at the National Swimming Championships.
C．People think Peng Liyuan, wife of President Xi Jinping, will draw great attention from people both at home and abroad.
D．It is reported that many college students have volunteered to serve in the 2014.Nanjing YOG.
党的十六大提出在21世纪头20年全面建设小康社会，这是因为（）。
A、我国还只是总体上达到小康水平
B、现在达到的小康还是低水平的小康
C、现在达到的小康还是不全面的的小康
D、现在达到的小康还是发展很不平衡的小康
