[yī cì]

once a week
一周一次

more than once
不止一次

once again
再一次

try once again
再试一次

Will once be enough?
一次就够了吗?

The increasing distance between thunderclaps meant the storm was moving away.
雷声隔得一次比一次久， 这意味着暴风雨正在过去。

I have been there once.
我到过那儿一次。

I've met her only once.
我只见过他一次。