给加粗字注音。
①夕日欲颓_________
②未复有能与其奇者__________
③藻、荇交横_________
①tuí②yù③xìng
According to the timetable, the train for Beijing ____ at four in the afternoon. [ ]
A. leaves
B. is leaving
C. will leave
D. leave
一物体以4m/s的线速度做匀速圆周运动，转动周期为2s。则该物体在运动过程的任一时刻，速度变化率的大小为（）。
A.2m/s2
B.4m/s2
C.0
D.4π/s2
