"开设游泳课"用英语可以表达为"offer swimming lessons"或"provide swimming lessons"。这两个短语的意思都是"to make swimming lessons available"，意思是为人们提供游泳课程。

来源：

这两个短语都是由动词"offer"和名词"lessons"构成的。"Offer"来自中世纪拉丁语"offerre"，意思是"to present for acceptance or rejection"，即"向人们提供供其选择的东西"。"Lessons"来自中世纪拉丁语"lectio"，意思是"a reading or lecture"，即"阅读或讲座"。

一些英文例句及其中文翻译：

We are offering swimming lessons for children this summer. (我们今年夏天为儿童开设游泳课。)
The community center provides swimming lessons for all ages. (社区中心为所有年龄提供游泳课。)
Do you offer private swimming lessons? (你们提供私人游泳课吗？)
I'm interested in signing up for swimming lessons. How do I do that? (我想报名参加游泳课。我该怎么做？)