I do not yet know how to swim breaststroke effectively.

我还不知道如何有效地进行蛙泳。

《柯林斯英汉双解大词典》

"I see you know how to swim very well," she said, watching him do the backstroke.

“看来你很会游泳啊”，她一边说一边看他仰泳。

《柯林斯英汉双解大词典》

Kids who don't know how to swim should wear life jackets.

不会游泳的孩子应该穿救生衣。

youdao

Only about 35% of Americans know how to swim, and only 2% to 7% swim well, Osinski says.

CNN: Water safety expert: 'Drowning doesn't just happen'

"I thought, oh wow she really doesn't know how to swim, despite what everyone thinks, " says Ms. Rothenhaus.

WSJ: See Spot Swim: Remedial Lessons Put Pooches in the Pool

Not only did Einstein love to sail and not know how to swim he often took unnecessary chances while sailing.

FORBES: Einstein at the Beach: The Hidden Relationship Between Risk and Creativity