Background: Deep in the bowels of Cheyenne Mountain is a city-like military complex that once served as North American Aerospace Defense Command (NORAD) 's center.

背景材料：在夏延山的深处像一座城市一样的军事综合隧道，一度作为北美防空司令部(NORAD)的中心。

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The defense wall and the deep and wide ditch surround the whole complex, not as part of a military fortification rather as a form of restricted ceremonial isolation.

防护墙和既深又宽的水渠环绕着整个建筑群，它们并不是军事防护工事的一部分，而只是一种仪式上的限制隔离。

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Just like the Great Wall, the Xi 'an City Wall was originally built for defense, with watchtowers and even a deep moat and drawbridges.

和长城一样，西安古城最开始建造是用于防御，不仅有瞭望塔，甚至还有很深的护城河及吊桥。

youdao

All of that is a way of simply saying it was deep and abiding and well-rehearsed thousands of pages were written in defense of slavery.

所有我提到过的著作都是,为了表达深入人心的,持久不变的奴隶制,上千页的著作都是对其的辩护

耶鲁公开课 - 美国内战与重建课程节选

Deep cuts in defense spending and fewer exports also contributed to the decline.

WSJ: US factory output falls on weak auto production

If the trigger had been balanced, if it had included not just cuts in defense and cuts in non-defense discretionary spending, but also revenue, the cuts would have been less deep in both non-defense and discretionary spending.

WHITEHOUSE: The White House

This has allowed China to make substantial progress, nurturing deep economic, political and defense ties.

CENTERFORSECURITYPOLICY: An African ��Marshall Plan��