我真的必须学习急救的基础知识。

I really must learn ___the ___basics of first aid.

去年，我选择带团队去帆船和潜水旅行，因为我已经知道帆船和潜水的基础知识。

Last year, I chose to take groups on sailing and diving trips because I already knew ___the ___basics of sailing and diving.

在开始高级课程之前，你需要掌握基础知识。

Before starting the advanced course, you need to master ___the ___basics.