【简答题】Direction: Write a composition about 2 50 words on the following topic: EDUCATION AS A LIFELONG PROCESS You are to write in three paragraphs. In the first paragraph, state clearly your viewpoint. In t...
【单选题】在图示平面机构中,滑块 B 可在水平滑道内运动,套管 H 可在导杆 OC 上自由滑动。已知: P = 60 kN , Q = 50 kN , OA = L 1 = 25 cm , AB = L 2 = 20 cm , b =16 cm , 不计各构件自重及各接触处摩擦。试用虚位移原理求机构在图示位置 (OC 水平 ) 平衡时,套管 H 的位 置 x 为 。