Swimming under water takes away all other aspects or worry about balance or breathing so you can focus just on how your arm connects with the water.

在水下游泳或其他方面需要把所有担心平衡或呼吸，这样你就可以在你的手臂聚焦在如何连接着水。

On pool deck, demonstrate correct timing of breathing/arm action.

站在泳池边，专注于呼吸和胳膊动作在时间上的正确配合；

Start with single arm fly, breathing low on every stroke, with one goggle in the water, using a straight arm recovery to simulate butterfly.

开始以单臂飞，呼吸每一拍，低一睁眼浸在水里，用直臂开始模拟的蝴蝶。