— Who will go to the airport to meet Mary?
— I will. I ________ her several times. I can find her easily.
A:met
B:have met
C:had met
D:will meet
探究声音的传播条件
在地面上,将一个小球以v=20m/s初速度竖直上抛,则小球到达距抛出点10m的位置所经历的时间为(g=10m/s2)( )