U-s
abbr. upper-stage 上级，顶级
🗣️ 情景例句
I have no spare time for hobbies or activities.
我没有时间去爱好什么。
You look very tried tonight.
今晚你看起来很疲倦。
Finding planets is proving hard enough, but finding life on them will prove infinitely more difficult.
寻找行星证明相当困难，但是要在行星上发现生命会变得无比艰难。