Ossein
n. 骨胶原\\n[化] 骨胶原; 生胶质
🗣️ 情景例句
You look very familiar. Have we been introduced before?
你看起来很面熟，我们以前互相介绍认识过吗？
There must be someone behind the door.
门后必然有人在。
It is fairly clear that sleeping period must have some function,
很清楚，睡眠必然具有某种作用。