adv.一次,一趟,一倍,曾经,一旦
conj.一旦…就…,一经
n.一次,一回
It had once been the home of a wealthy nobleman.
这里曾是一个有钱贵族的宅邸。
He once told an interviewer that he didn't even like rock music.
他曾告诉一位采访者,他甚至都不喜欢摇滚乐。
We tend to meet up for lunch once a week.
我们往往每周共进一次午餐。