Particle number density
[化] 平均密度
🧩 词语组成解析
🗣️ 情景例句
You're in sad condition.
你的健康很成问题。
Mac always has to run to catch his train.
麦克常常为了赶乘火车而奔跑。
At the age of twelve years, the human body is at its most vigorous.
人体在12岁时是生命力最旺盛的时期。