swamplands remain a stronghold for amphibians. 沼泽仍然是两栖动物的根据地
tribes are uniting in some secret stronghold, 许多部落齐聚到一处秘密要塞
The Gobi, hostile though it is, is their last stronghold. 戈壁尽管环境险恶 却是它们最后的据点