Backstepping
n. 逐步退焊法\\nv. 往后退（backstep的ing形式）
🗣️ 情景例句
There are three things that have to be done first, Harry.
首先我们必须做三件事， Harry。
Light come,light go.
易得则易失；来得容易去得快。
How long have you been learning English?
你学英语有多久了？