advance guard

基本解释

" is from the Greek and means "an advance guard".
一词来自希腊语，意思是提前防卫（预防）。
Mobile phones, it seems, are the advance guard for mobile-broadband networks that will extend internet access to the whole of mankind.
手机似乎已在帮助全人类接入移动宽带网络中扮演起了排头兵的角色。
Uniformed military personnel patrolled Washington street corners, the advance guard of a massive security presence planned for the oath-taking, inaugural speech, parade and other festivities.
为了保障总统宣誓仪式，就职演讲，游行和其他庆祝活动的开展，政府部署了大规模的安全力量。身穿制服的军人在华盛顿的街角巡逻，他们是安保的前沿阵地。

The avant-garde (literal translation, advance guard) valiantly leads the rest of the culture into the uncharted future.
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And in areas such as Schengen, there can be little real objection to an advance guard plunging ahead.
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Mr Clinton's advance guard on a recent visit to Britain was as big as Mr Blair's entire executive staff.
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a military unit sent ahead of a main body to find gaps in enemy defences, clear away minor opposition, and prevent unexpected contact