【简答题】Dear Mr. White, Our class is going out for 1 this Saturday, May 7th. We would like to 2 you to join us. We are going to Qingyun Mountain. We will 3 the bus at the school gate at 7:50 in the morning. T...
【多选题】倾角为37°的光滑斜面上固定一个槽,劲度系数k=20N/m、原长l 0 =0.6m的轻弹簧下端与轻杆相连,开始时杆在槽外的长度 =0.3m,且杆可在槽内移动,杆与槽间的滑动摩擦力大小F f =6N,杆与槽之间的最大静摩擦力等于滑动摩擦力。质量m=1kg的小车从距弹簧上端L=0.6m处由静止释放沿斜面向下运动。已知弹性势能E p ,式中x为弹簧的形变量。g=10m/s 2 ,sin37º=0.6。关...
【单选题】We would like to explain that ______ long-term pleasant cooperation, most of our suppliers draw ______ us ______ 60 days’ sight documents ______ acceptance.