A:13.5L
B:9.0L
C:16.8L
D:15.7L
Mike can play chess, _________he can’t play cards.
已知某个车轮旋转的角度α(弧度)与时间t(秒)的函数关系是α=2π0.64t2(t≥0),则车轮启动后第1.6秒时的瞬时角速度是( )
Every year thousands of trees _________ to improve the environment.