Upgradable
a. 能提到更高一级标准的(=upgradeable)
🗣️ 情景例句
Hello.
你好！
All the neighbors helped us move in.
邻居们都帮忙为我们搬家。
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）