1. Green barrier is nowadays trade obstacle that enterprises have to face in international trade. 绿色壁垒是当今国际贸易中企业不得不面对的贸易障碍。
2. Using the curving characteristic at the normal temperature, designs the more perfect sound barrier. 利用常温下可自然弯曲的特性，设计出更加完美的声屏障。
3. Although the UML defines a precise language, it is not a barrier to future improvements in modeling concepts. 尽管UML定义一种精确的语言，它不是到在建模概念的未来改进的一个障碍。
英英解释
n.
1. a structure or object that impedes free movement
2. any condition that makes it difficult to make progress or to achieve an objective
3. anything serving to maintain separation by obstructing vision or access
