Jetpack
喷气发动机组件
🗣️ 情景例句
Why do we need a swimming pool? Everyone in the family hates swimming!
我们需要游泳池做什么呢？家里人都讨厌游泳。
Don't make trouble.
别惹麻烦！
a trough (the lowest point), a height (the vertical distance from the trough to the crest),
波谷（最低点）、浪高（从波谷到浪峰的垂直距离）