Straight down the line

Pilots from different countries understand body signals if they have the correct training. When you wave your arms up and down in a straight line, it means "yes".

如果接受了正确的训练，来自不同国家的飞行员都能理解身体信号。当你沿一条直线上下摆动手臂时，就表示“是”。

Then the wise man took a piece of paper and drew a straight line down the middle.

然后，智者拿出一张纸，在中间画了一条直线。

Stand side-on to a bench with your closest hand and knee on the bench, back parallel to the floor (neck in line) and a dumbbell in your other hand, arm hanging straight down.

侧立于练习凳一侧，靠凳一侧的手与膝支撑于凳。背部与地面平行(与颈部成一条直线)，另一侧手手持哑铃，手臂垂直悬于体侧。