活动铰支座的约束力方向是确定的,垂直于支承面指向铰链
A. 对
B. 错
Listen to the expressions of time and put them down in the blanks.
作用在同一物体上的两个力,使物体处于平衡的必要和充分条件是:这两个力大小相等、方向相反、沿同一条直线。
A. 对
B. 错
1. What are the legal ages for girls and boys to marry in India?
A. 16 for girls and 18 for boys
B. 18 for girls and 21 for boys
C. 11 for girls and 13 for boys
D. 20 for girls and 22 for boys