行軍篇 NO.3：

凡地有絕澗、天井、天牢、天羅、天陷、天隙，必亟去之，勿近也。
吾遠之，敵近之；吾迎之，敵背之。
軍旁有險阻、潢井、葭葦、林木、翳薈者，必謹覆索之，此伏奸之所處也。

這句啥意思：

凡遇到或通過“絕澗”、“天井”、“天牢”、“天羅”、“天陷”、“天隙”這幾種地形，必須迅速離開，不要接近。
我們應該遠離這些地形，而讓敵人去靠近它；我們應面向這些地形，而讓敵人去背靠它。
軍隊兩旁遇到有險峻的隘路、湖沼、水網、蘆葦、山林和草木茂盛的地方，必須謹慎地反復搜索，這些都是敵人可能埋設伏兵和隱伏奸細的地方。

英文這么說：

Country in which there are precipitous cliffs with torrents running between, deep natural hollows,confined places, tangled thickets, quagmires and crevasses,should be left with all possible speed and not approached.
While we keep away from such places, we should get the enemy to approach them; while we face them,we should let the enemy have them on his rear.
If in the neighborhood of your camp there should be any hilly country, ponds surrounded by aquatic grass,hollow basins filled with reeds, or woods with thick undergrowth, they must be carefully routed out and searched;for these are places where men in ambush or insidious spies are likely to be lurking.

幾種地形的白話分析

絕澗：溪谷深峻，水流其間；天井：類似于盆地； 天牢：高山環繞，易進難出；天羅：草深林密，難以出入；天陷：地勢低洼，道路泥濘； 天隙：兩山相向，澗道狹窄。