你最喜欢哪种游泳姿势？

What's your favourite swimming ___stroke?

掌握正确的泳姿技巧对竞技游泳运动员至关重要。

Mastering the correct ___stroke technique is crucial for competitive swimmers.

蝶泳被认为是最难精通泳姿之一。

The butterfly ___stroke is considered one of the most challenging to perfect.