Vub
abbr. variable upper bound 可变上限，可变上界
🗣️ 情景例句
Try to think in English whenever possible.
尽可能用英文思维。
If the hen does not prate,she will not lay.
不叨叨的母鸡不下蛋。
I usually come by bus. What about you?
我平常乘公共汽车。你呢？