一年一度的季节性流感疫苗注射已经开始了，让许多成年人开始怀疑每年一次的流感疫苗注射是否适合他们。

The annual jab fest for the seasonal flu is already underway, leaving many grown-ups wondering if the annual stick in the arm is right for them.

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第二天，我们去玛莎葡萄园岛，开始每年一次的休假。

The next day we left for Martha's Vineyard on our annual vacation.

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商人们只在每年一次的广交会上被允许入境。

Businessmen were granted access once a year for the Canton Trade Fair.

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Even such concepts, such great American concepts let's call it that--as self-reliance about which Ralph Waldo Emerson may have written his greatest essay I go read Emerson's "Self-Reliance" at least once a year.

这样的观念,伟大的美国式的观念,让我们称呼它为,自助,这是拉尔夫·华尔多·爱默生写过的,最具影响力的作品,我每年至少读一次爱默生的《自助》

耶鲁公开课 - 美国内战与重建课程节选