A previously unknown extremist group has said it carried out Friday's bomb attack.
一个先前不为人知的极端组织声称实施了星期五的炸弹袭击。
《柯林斯高阶英汉双解学习词典》
Those who dared to launch out beyond the unknown waters became the discoverers of new lands.
那些敢于去人迹未至的海域航行的人成了新陆地的发现者.
《简明英汉词典》
