The train operates the 2,400-mile round trip once a week.

这列火车每周进行一次2400英里的往返旅行。

《柯林斯英汉双解大词典》

We went on a campaign trip once in Italy, and my wife spent the whole time worrying about bats getting into her hair.

我们有次在意大利露营，我的妻子一直在担心蝙蝠飞到她的头发里。

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Due to the influences in the solar system and from outside the solar system, the Earth will make her round trip once a year.

由于太阳和来自于太阳系之外的影响，地球的公转周期仍然是一年一次。

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Once,on a business trip to London, Charles Homer bought a set of drawing examples for his son to copy.

VOA: special.2010.07.25

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

And once each month, mail would arrive in California after a slow trip by wagon from Saint Louis,Missouri.

VOA: special.2009.05.28

Ward used his rank to shuttle his wife on shopping sprees, enjoyed a lavish beachfront trip and once accepted a Defense contractor's gift of going backstage to meet actor Denzel Washington.

CNN: U.S. General in charge of Horn of Africa fired

Trip interruption plans protect travellers who get stuck once their trip is underway.

BBC: Is travel insurance right for you?

By any standard, it has been an exhaustively splendid trip, crammed at once with private anxiety and lofty overviews of public strife.

NEWYORKER: The Lord of the Rings: The Return of the King