Keep Your Back Straight的意思|示意

Bent your knees, but keep your back straight.

屈膝，保持背部挺直。

Keep your front shin vertical, back knee straight, back heel lifted, and chest lifted.

保持前面小腿垂直地板，后膝伸直，后脚跟离地，胸腔上展。

So you want to take your shampoo, hold your arm straight up, keep your arm right next to your ear, and then simply bend your elbow to ninety degree, and then lift it back up.

你要拿起洗发水，手臂向上伸直，紧贴耳朵，然后只要将手肘向后弯曲90度，再将手肘伸直。

Keep your posture straight and erect. Your head should be up, your back straight, and shoulders level.

保持您的姿势挺而直，抬起头，挺直腰，双肩水平。

Keep your upper back and neck comfortably straight.

保持后背上部和颈部舒适挺直。

You should keep your back straight.

你应该把后背挺直。