跳伞运动员以5 m/s的速度竖直匀速降落,在离地面h=10 m的地方掉了一颗扣子,跳伞运动员比扣子晚着陆的时间为(扣子受到的空气阻力可忽略,g取10 m/s2)( )
A:2
B:2
C:1
D:2-2
— Han Tao _______ for school at seven o'clock in the morning.
— That's too early.