Systems
n. 体制, 体系；制度；系统（system的复数形式）
🗣️ 情景例句
And your legs don't hurt?
你的腿不酸不痛？
Time flies.
时光易逝。
Once the oxygen content of the air had risen to 25% it was ready to burn.
一旦氧气在空气中的含量达到25%，它就要燃烧。