求翻译：　　脸向上仰卧，双膝弯曲，并且将双足放于不稳固的物件上，如瘪皮球、小枕头或卷起的毛巾(8至15厘米高)。左腿伸直，收缩臀肌，抬举胯部，然后再将胯放回地面。做12至15次，然后换另一侧做。整套动作重复2组。是什么意思？

Lying face up, knees bent, feet and will not put in a solid object, such as the deflated ball, small pillow or rolled up towel (8 to 15 cm high). Left leg straight, contract the gluteal muscle, flattering hip, hip and then back into the ground. Do 12 to 15 times, then for the other side to do. Repea

ABS face upward, his knees bent, feet and will be placed in an unstable object, such as ball deflated, small pillow or rolled towel (8 to 15 cm high). Stretch out your left leg, contraction, lift my ministry." And then put back on the ground. Do 12 to 15 times, and then switch to another side. Repea

　　The face lies supine upwardly, the double knee is curving, and puts both feet on the unstable thing, like the shrivelled rubber ball, the small pillow or curl up towel (8 to 15 centimeters high).The left leg unbends, the contraction gluteus, favors the hip department, then returns again the hip th

　　Lay the face up, knees bent and feet placed on unstable objects, such as a flat ball, a small pillow or rolled towel (8 to 15 cm high). The left leg straight, contraction of gluteal muscles, flattering crotch, and then the hip and back on the ground. 12 to 15, and then change the other side. Entir

　　Lay the face up, knees bent and feet placed on unstable objects, such as a flat ball, a small pillow or rolled towel (8 to 15 cm high). The left leg straight, contraction of gluteal muscles, flattering crotch, and then the hip and back on the ground. 12 to 15, and then change the other side. Entir