壁垒森严

壁垒森严 [bì lěi sēn yán]

1. ■ （防守很严密） strong defense preparations; a well-organized institute; strongly fortified; an unassailable stronghold; be heavily; closely guarded; The military breastwork is stiff.

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常用词组

1. ■ （界限划得很分明） sharply divided