The typical trench system in World War I consisted of a series of two, three, four, or more trench lines running parallel to each other and being at least 1 mile (1.6 km) in depth.

第一次世界大战时典型的堑壕体系由2至4条以至更多的一系列壕沟组成，壕沟之间彼此平行，而且纵深可以达到1英里（合1.6公里）。

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The world of 1, 000 years ago was a miserable place: dirty, war-scorched and mostly illiterate.

1000年以前的世界很是悲惨：肮脏，战乱，大多数人目不识丁。

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World War Three is just around the corner and the planet is teetering on the brink 1 of all-out conflict - according to people in major Western nations, at least.

第三次世界大战即将爆发，世界即将面临全面冲突——至少主要西方国家的民众是这样想的。

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At the beginning of World War 1, the squadron moved to France and were the first to land there.

BBC: Montrose Air Museum

About 60 oil paintings, murals and sketches gathered together from Moscow, St Petersburg and Paris focus on the eight years Chagall spent in his home town of Vitebsk in Russia during World War 1, the Bolshevik Revolution and its aftermath.

BBC: Chagall and the art of passion and drama

In the 59 bombing raids that flattened Plymouth during World War II more than 1, 000 high explosives fell on the city.

BBC: Plymouth's 'first' WWII bomb site discovered