Fenchone
葑酮, 1, 3, 3-三甲基-1, 4-桥亚甲基-2-环己酮
🗣️ 情景例句
I would like to send this by registered mail, please.
我想把这封信挂号寄出。
To learn how to count
学习记账
and at the most critical juncture we took turns in watching that point.
在最紧急的时刻，我们轮流监视那段河流的险情。