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- You should keep your back straight. 你应该把后背挺直。
- Hold your head up and keep your back straight. 请把头抬起来，腰直起来。
- Keep your back straight while you walk. 走路是背挺直.;不要摸栏杆
- Bend your knees, keeping your back straight. 膝盖弯曲，背部挺直。
- If you prefer to sit on a chair, keep your legs relaxed, and be sure always to keep your back straight. 若你想坐在椅子上,脚要放松,背要挺直。
- Keep your back straight. 挺直你的背。
- My grand mother is very keen on good manners: brushing your teeth, keeping your back straight and all that jazz. 我奶奶可讲究好习惯了,什么要刷牙,背要直啦那一套。
- Please keep your hands behind your back. 请把手放在背后。
- Set your feet shoulder-width apart, and keep your knees slightly bent, back straight, and eyes focused straight ahead. 双脚与肩同宽，保持膝部稍弯，后背挺直，双眼注视前方。
- Kneeling： Kneel upright with your weight on your knees and your back straight. 行双膝跪礼时，是直式的跪，身体的重量集中于双膝，背部要直。
- Now you are in the neutral position keep your arms comfortably extended, knees flexed (6), back straight and body leaning back to counterbalance the weight of the rig. 现在你就站在中立位置上了，尽情舒展双臂，膝盖弯曲，背挺直，身体向后倾斜，平衡横衍的重量。
- Please keep your hands behind your backs. 请把你们的手放在背后。
- You must keep your hands behind your backs. 你们必须把手放在背后。
- You should keep your hands behind your backs. 你们要把手放在背后。
- Posterior flye.Sit on a balance ball with your feet together and your back straight at a 45-degree angle to your thighs. 两脚并拢坐在健身球上，背部与大腿呈45度角。
- Burrow the tailbone down toward the floor, and keep your back muscles soft. 将尾椎骨尽量靠向地板方向以使背部肌肉保持柔软。
- Lie on your back and lift both feet together into the air, keeping your knees straight. 后背着地躺下，把双脚并拢伸到空中，保持双膝直立。
- Ben：Yap, when you do the push up make sure your chest touches the floor and keep your back traight. 嗯~当你做伏地挺身时要确定胸部要碰到地然后保持背部挺直!
- Ben: Yap, when you do the push up make sure your chest touches the floor and keep your back traight. 嗯~当你做伏地挺身时要确定胸部要碰到地然后保持背部挺直!
- Try to keep your body upright, but slightly tilting forward so you do not arch your back. 尽量保持身体直立，但是稍微向前倾斜，因此你不用拱起背。
