Polyketone
聚酮
🗣️ 情景例句
How ofter have met with our competitors?
你多久遭遇我们的竞争对手一次？
You'll hurt your arm, if you don't take care.
你不专心的话，就会伤到你的手指。
OK. Let's go to Number 1 Machine Shop.
好吧，让我们去第一机械车间。