这双手敏捷而有力地在水中扑打着，不停地向下摆动，迫使他浮向水面。

They beat the water vigorously with quick, downward strokes, forcing him to the surface.

youdao

膝盖和脚应当向上刚好摆动到水面的位置，然后就应当向下摆。

You want you knees and your feet to just kind of come to the surface, and then go back down.

youdao