处于临界平衡状态的压杆可以维持直线平衡,也可以维持微弯状态的平衡。
查看答案
当干扰力消失后杆件在新位置的平衡称为临界的平衡。
A. 对
B. 错
杆件丧失了原有直线形状的稳定性,这类破坏称为丧失稳定性。
A. 对
B. 错
The writer never gets up early on Sundays. _____________________.
A. He often gets up at 8 o'clock in the morning.
B. Sometimes he stays in bed until lunchtime.
C. He seldom stays in bed late.
D. He always stays in bed until lunchtime.
Last Sunday, it's raining again. "____________!" The writer thought.
A. It's a terrible day!
B. This is a terrible day!
C. What a terrible day!
D. What a beautiful day!
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