Understructure
n. 基础, 下层结构
🗣️ 情景例句
Don't forget to use primer first when you paint the house.
刷房子之前别忘了刮底漆。
Track 4 at 9:30.
9点30分，4轨道的车。
I counted seven old cars and three old refrigerators.
我数了一下，有7辆旧汽车和3上旧冰箱。