题目

阅读下面短文，从短文后各题所给的A、B、C和D四个选项中，选出可以填入空白处的最佳选项。 The stage lights dimmed,and I took a quick look from behind the heavy black curtains into the audience.Blinded by the lights, I quickly1. It seems that a greatnumber of eyes were looking at me. I took a deep 2as the music of my dancebegan to play. I entered the stage and began my3, the graduation test ofthe classical Indian dance. After a decade of learningthis art form, I had4been considered ready totake on the most difficult act. The test is the most important event in如图所示，以A、B为端点的半圆形光滑轨道固定于竖直平面内，一粗糙水平面BC与半圆形轨道相切于B点。质量为2m的物块1被轻放在水平匀速运动的传送带上G点，运动到A时刚好与传送带速度相同，然后经A沿半圆轨道滑下，再经B滑上BC，在C处与质量为m的物块2相碰（相碰没有能量损失）。倾斜角为37°、高为3R斜面与BC和水平地面FE相接，已知CEF表面有一层很厚的细砂，以阻止物块运动。物块均可视为质点，半圆半径为R，BC长LBC =2R。G距A为S=5R，物块与传送带、物块与BC间的动摩擦系数均为μ=0. 5，重力加速度取g。（sin37°=0.6，cos37°=0.8）（1）求物块滑到B点的速度大小。（2）求物块1与物块2碰撞后，在空中运动的时间。