图5-9-13所示单元体的应力状态按第四强度理论，其相当应力σr4为：（）
A.3σ／2
B.2σ
C.7v2σ／2
D.5v2σ／2
参考答案：C
法国作家罗曼·罗兰的长篇小说_____________反映了一个有才华的音乐家在资本主义社会中遭遇失败。
---I’ve heard you ___ here. What is it like？
---Very hard. But as long as the pay covers the expenses for my next school term, It’s ok.
A．work
B．have worked
C．are working
D．will work
