1. The fortress was the nucleus of the ancient city.
   这城堡是这座古城的中心.
2. The easiest way to capture a fortress is from within.
   堡垒最容易从内部攻破。
3. an impenetrable fortress.
   无法通过的城堡
4. An invincible fortress or stronghold.
   难攻打的城堡或要塞
5. They thought they saw the emergence of a Fortress Europe.
   他们认为他们看到了一个欧洲堡垒脱颖而出。

　1个名词解释