问题
选择题
______ our arriving at the airport, we were given a warm welcome by the local people. [ ]
A. With
B. At
C. Upon
D. Until
答案
答案：C
搜题请搜索小程序“爱下问搜题”
______ our arriving at the airport, we were given a warm welcome by the local people. [ ]
A. With
B. At
C. Upon
D. Until
答案：C
光滑圆弧的质量为M的曲面体，已知曲面顶端切线竖直。若M未能越过曲面体，求球到达最高点时曲面体的速度以及曲面半径的最小值。