把衣服沿肩线折向前面，检查衣领(领圈)后面。

Fold garment forward at shoulders and inspect back neck.

youdao

从上面看皱纹的流向，无论哪一部分都大致垂直于肩线。

Look at the flow of wrinkles from above, no matter which part is roughly perpendicular to the shoulder line.

youdao

如果你总是在仰泳划水的时候手臂过肩线，那么这个双臂练习就会让你很难做到，因为你必须在移臂时手臂交叉才能做到那样。

If you consistently over-reach on your backstroke pull, double-arm makes this very tough to do, because you have to cross your arms during the recovery to accomplish that.

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