在触壁前的最后一个划水动作结束后，头可以潜入水中。但在触壁前最后一个完整或不完整动作周期中，头的某一部分应露出水面。

The head may be submerged after the last arm pull prior to the touch, provided it breaks the surface of the water at some point during the last complete or incomplete cycle preceding the touch.

youdao

在触壁前的最后一个划水动作结束后，头可以潜入水中。但在触壁前最后一个完整或不完整动作周期中，头的某一部分应露出水面。

The head may be submerged after the last arm pull prior to the touch, provided it breaks the surface of the water at some point during the last complete or incomplete cycle preceding the touch.

youdao