why does the daughter want to go out?
A. she wants to get away from her father.
B. she doesn't like the taste of the supper.
C. she has finished eating
D. she has to attend a lecture.
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当杆件处于弯扭组合变形时,对于横截面的中性轴有这样的结论,正确的是:
A. 一定存在;
B. 不一定存在;
C. 一定不存在。
塑性材料制成的圆截面杆件上承受轴向拉力、弯矩和扭矩的联合作用,其强度条件是 。
A. σr3=N/A+M/W≤|σ|
B. σr3=N/A+(M2+T2)1/2/W≤|σ|
C. σr3=[(N/A+M/W)2+(T/W)2]1/2≤|σ|
D. σr3=[(N/A)2+(M/W)2+(T/W)2]1/2≤|σ|
讨论各种基本变形时,对变形特征提出共同的基本假设是____ 。
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