任务型阅读。

                           Poster

                  New Year's Day Party

                  Some Chinese food

                  Pop music

                  Place: Class 3, Grade 7

                  Date: 12, 28, 2004

                  Welcome all the students

Questions:

1. What party is it ?

    ____________________________________________________________

2. Where is the party?

    ____________________________________________________________

3. When is the party?

    ____________________________________________________________

4. Who can come to the party?

    ____________________________________________________________

5. What can people do at the party?

    ____________________________________________________________

管子弯曲是管子在外加力矩作用下产生弯曲变形的结果。在弯曲变形进程中，管子外侧管壁受拉应力作用，而内侧管壁受压应力作用，接近中心的地方有一层管壁即不受拉应力作用也不受压应力作用，这一层管壁称为中性层。