单选题
图1-1-20所示结构中,杆b的内力Nb应为下列何项数值?()

- A.N<sub>b</sub>=0 <br/>
- B.N<sub>b</sub>=<img src="https://timg.fentiku.com/javaimportItems/7ccedf2d1910465fbfe69efadd4fae23/images/9cbca.png" />P <br/>
- C.N<sub>b</sub>=P <br/>
- D.N<sub>b</sub>=<img src="https://timg.fentiku.com/javaimportItems/7ccedf2d1910465fbfe69efadd4fae23/images/9d12a.png" />P <br/>
正确答案:A
