His legs flail about as if independent from his body.

他那双脚跳舞时 好像跟身体分离了一样。

His legs flail about as if independent of his body!

他的腿相互敲打, 就象不属于他的身体!

My legs were flailing about and I tried to control my limbs, and get myself in order.

我的腿在乱晃， 我试图控制自己的四肢， 让自己保持秩序。

Heavily injured ants, however, flail their remaining limbs about and spin on their backs, becoming so uncooperative that they're left behind.

然而，受了重伤的蚂蚁会挥动剩余的四肢并在背上旋转，变得非常不合作，以至于它们被抛在了后面。