一次 的英文怎麼說?

[1] in/at one sitting
  in/at one go[2] once
  one time

in one sitting 非常貼切常用，例如:

How many chin ups can you do in one sitting? = 你可以一次連續做幾次引體向上?

I read the book in one go = 我一次就把書全部讀完了

in one sitting 跟 in one go 是一樣的意思。

I've been to Italy once. = 我去過義大利一次