【多选题】下面关于光滑圆柱铰链(固定铰)约束表述正确的是?
A.
限制被约束物体在垂直于销钉轴线的平面内任何方向的位移
C.
约束力作用在与销钉轴线垂直的平面内,并通过销钉中心,方向待定
【判断题】光滑面约束对物体的约束力作用在光滑面与物体的接触点处,沿接触面处的公法线,是指向被约束物体的压力。
【单选题】在加工阶段划分中,保证各主要表面达到图样所规定的技术要求的是( )。
【单选题】Suppose a small country experiences economic growth which leads to an increased willingness to trade. The country’s terms of trade will _____ because the prices of its exports will _____ relative to t...
B.
b. improve; not change
C.
c. remain unaffected; not change
D.
d. remain constant; fall
【单选题】Suppose a small country experiences economic growth which leads to an increased willingness to trade. The country’s terms of trade will _____ because the prices of its exports will _____ relative to t...
C.
remain unaffected; not change
【单选题】以下哪一种运输适合在陆地地表进行长距离的运输?
【多选题】画构件受力图时需要注意以下那些事项?
A.
画约束力,一定要按约束性质来画。即要明确是何种约束类型:光滑表面约束、固定铰支、活动铰链、滚动铰支、固定端等;
B.
注意作用力与反作用力的画法。作用力和反作用力等值、反向、共线且分别作用在两个物体上;
C.
会判断二力杆,并根据二力平衡条件确定约束力的方向;
【简答题】Which country leads the world in research and developmentspending?A. United States B. Japan C. China D. Germany