四、回旋球在送球的同时,手腕、手指要向上扭转,拇指孔由12时转至1时,使手掌朝外,扭转手腕(见图)。步法、姿势与其它投球法基本相同。回旋球并不容易控制,所以应尽量避免,但是,有时候非得回旋球才能把剩下的球瓶击倒。因此,还是要经常练习,以便掌握。女性的手肘是顺着内侧弯曲的,所以,只要自然投球,往往容易出现回旋球。 Fourth, the swing ball At the same time to send the ball, wrists, fingers to turn up, thumb hole from 12 o’clock to 1, so that the palm outwards, twist the wrist (see photo). Footwork, posture and other pitching method is basically the same. The swing ball is not easy to control, so try to avoid it, but sometimes you have to swing the ball to knock down the remaining ball. Therefore, we still need to practice regularly in order to grasp. Female elbows are curved along the inside, so, as long as the natural pitching, often prone to swing ball.