The jumper's foot must not mark beyond the takeoff line at the far end of the board.
运动员的脚不允许超过起跳板前沿的起跳线。
2
The rubber rope tied to the jumper's ankle is long enough to ensure that he or she will enjoy the "free fall" in the air for a few seconds.
绑在跳跃者踝部的橡皮条很长，足以使跳跃者在空中享受几秒钟的“自由落体”。
3
Through biomechanical analysis of top Chinese long jumper's take off, we learned that the moving track, speed, displacement of body's center of gravity and kinematics character of leg in the take off.