A.5~10m/s B.5~15m/s C.10~20m/s D.5~25m/s
A.1-5mm B.10-15cm C.15-20mm D.25-30mm
A.進(jìn)入大帶輪處 B.離開(kāi)大帶輪處 C.進(jìn)入小帶輪處 D.離開(kāi)小帶輪處