He stopped at the door, waiting in vain for her to acknowledge his presence.

他停在门口，徒然地等着她跟自己打招呼。

《柯林斯英汉双解大词典》

Erewhile I sought it, and sued in vain.

不久前，我寻找它，却徒劳无功。

youdao

Our efforts were not in vain.; we didn't waste our energy.

我们的力气没有白费。

《新英汉大辞典》

It is rather for us,the living, we here be dedicated to the great task remaining before us - that,from these honored dead we take increased devotion to that cause for which they here, gave the last full measure of devotion - that we here highly resolve these dead shall not have died in vain;

VOA: special.2011.02.07

"For we assert," he says, "nature does nothing in vain and man alone " among the animals has speech.

他说，“因为我们主张自然演变并不无道理,而人类独立于其它动物之外,是因为我们有辩论能力。

耶鲁公开课 - 政治哲学导论课程节选

Specifically you'll see that the rationale for observing the Sabbath is different. God's name in Deuteronomy 5 is not to be used in a vain oath as opposed to a false oath. There are differences in the meaning.

你会发现两者对守安息日习俗的论述是特别不同的,《申命记》第五章的描述是，不可以妄称上帝的名,而不是不可以以上帝的名义作假誓，它们表达的意思。

耶鲁公开课 - 旧约导论课程节选

Some of these were contained electronically so much of the shredding was in vain.

FORBES: Rajaratnam Evidence -- Where Are The Emails?

My kids usually pitch in, flipping over sofa cushions, rummaging through their toy box in vain.

WSJ: Track Your Lost iPhone and Other Gear With These Gizmos

West tried in vain to resuscitate her son as bystanders called 911 for help.

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