It's a racquet moving low to high that stays vertical through the contact area and brushes up at the equator (the imaginary line around the center) of the ball.
It's a racquet moving low to high that stays vertical through the contact area and brushes up at the equator (the imaginary line around the center) of the ball.
是一个由低往高移动的网拍经过接触区域保持垂直而且在球的赤道（在中心周围的想像线）往上刷过。