Mobile sources
[经] 机动的来源
🧩 词语组成解析
n. 输入源；发起者；来源（source的复数）
🗣️ 情景例句
Is there any discount on bulk purchases?
我多买些能打折吗？
Track 4 at 9:30.
9点30分，4轨道的车。
It was my first flight. I was nervous when the plane took off.
我第一次坐飞机，起飞时我有点紧张。