abbr. 概率分部函数（Probability Distribution Function）
🗣️ 情景例句
What's that?
什么问题？
Improve your time and your time will improve you.
珍惜时间，时间才会珍惜你。
They had a single aim, a solitary goal -- the top!
他们只有一个目标，唯一的目标 -- 顶峰！