周公制礼
参考答案：
即在周公主持下，对以往的宗法传统习惯进行补充、整理，制定出一套以维护宗法等级制度为中心的行为规范以及相应的典章制度、礼节仪式。
GK型制动机是通过改变制动缸容积来实现空重车调整作用的。
The figure above is a regular hexagon with center H, The shaded area is a parallelogram that shares three vertices with the hexagon; its fourth vertex is the center of the hexagon. If the length of one side of the hexagon is 8 centimeters, what is the area of the unshaded region
