Stepped construction
[化] 阶梯式结构
🧩 词语组成解析
v. 踏；行走（step的过去式和过去分词）
🗣️ 情景例句
It's John. Didn't you recognize my voice?
我是约翰。你没听出我的声音？
To watch the accident
观察意外事故的现场
Once waves have been generated,
一旦波浪形成，