The troops rushed back onto the chopper and took off - but a head count showed one man was missing.

士兵们迅速回到直升机上，起飞了，但清点人数后发现一人失踪。

《柯林斯英汉双解大词典》

The monitor did a head count.

班长点了一下人数。

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Your enterprise needs to establish a head count of persons to perform event-driven double keying to avoid the time delay of a nightly batch update.

您的企业需要建立人头计算来执行事件驱动的双密钥生成，从而避免由于夜间批量更新造成的时间延迟。

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But perhaps a head count is not the best way to measure importance.

WSJ: A Library With a Pedigree | American Kennel Club Research Library | By Joanne Kaufman

Eisenberg was missing from his room during a head count Sunday afternoon at the Calumet Transitional Housing Unit in Manchester.

WSJ: Clinton office hostage taker found, arrested in NH

It means the host needs a definite head count for the planned event, and needs it by the date specified on the invitation.

FORBES: Importance of the RSVP