surround的被动形式

surround是一个英文单词，作为动词基本含义为围绕环绕(使)包围，围住与…紧密相关喜欢结交（某类人）作为名词基本含义为(物品的)边，饰边周围复数:surrounds 第三人称单数:surrounds 现在分词:surrounding 过去分词:surrounded 过去式:surrounded。

例句为The castle was originally surrounded by a triple wall， only one of which remains.这座城堡最初由三重墙环绕而成，现在仅存一道。

High hills surround the valley.高山环绕峡谷。