He tried to speak, but for once, his voice had left him.

他试图说话，但这一次，他已说不出声。

《柯林斯英汉双解大词典》

My father glanced at my mother and shrugged, but for once he didn't ask who before unchaining the safety latch.

爸爸耸耸肩，扫了眼妈妈，平生头一遭他没先问是谁就解开了安全闩。

youdao

Wuxi is famous for its water but it once had trouble because of water.

无锡因水著名，也曾因水而困。

youdao

Once again,he said the war was not a struggle for the Union, but a fight to free the slaves of the south.

VOA: special.2009.10.22

Never go back. Find another. Leave at once. Go for a long trip again, but this time we'll go wherever I want, won't we?" I nodded. My Lolita.

绝不会去，另找一所学校，马上走，再去长途旅行，不过这次去我想去的地方，好吗？“我点头，我的洛丽塔。

耶鲁公开课 - 1945年后的美国小说课程节选

But once you get there, you're very disappointed for several reasons.

但是一到那，你就发现有很多原因让你觉得相当失望。

Let's 课堂 - SpeakingMax英语口语达人

But for once the main action will be that crucial vote in the Lords.

BBC: Week ahead

We know this is a serious business, but for once, we'd love an anatomically correct housing to be developed for it.

ENGADGET: Alt-week 8.25.12: robotic noses, Nodosaurs and Space X launches again

But for once the international political momentum is working in Somalia's favour.

ECONOMIST: Surprising Somalia