Alum
n. 明矾, 矾, 校友\\n[化] 明矾; 钾铝明矾
📖 牛津释义
alum
n[U]
white mineral salt used in medicine and in dyeing 明矾, 白矾（用於医药及染色）.
🗣️ 情景例句
I got it!
我知道了。
Is that a book?
那是一本书吗？
As a reasonable guess, they might, on an average, be 100 light years away.
据合理推算，外星人离我们平均距离也有100光年之远