钢筋混凝土受弯构件挠度计算中采用的最小刚度原则是指在（）弯矩范围内，假定其刚度为常数，并按（）截面处的刚度进行计算。
参考答案：同号；最大弯矩
Wang Liqin _____ the national team in 1998 and then he _____ a lot of ping-pong matches.[ ]
A. joins ; takes part in
B. joins ; took part in
C. joined ; takes part in
D. joined ; took part in
OSI模型中，______管理数据的交换。
