英语正确吗

不对，因为before 已经是说明you know 这个动作是发生在过去的了，因此疑问句中的助动词必须是完成时，也就是 Have you known it before，强调过去动作对现在的影响，过去你知道了吗？强调“知道”这个动作的影响

right wrong【海的尽头没有鱼.】

right true

Her parents eventually admitted that to their relief,their daughter has turned into an adult.可以改成，Her parents eventually admitted that， to their relief, she has turned into an adult.她的父母最终承认，让他们松口气的是，她已经长大成人。

不正确, has应改成:had 。因为主句用的过去式admitted，宾从的动作发生在主句之前，故用过去完成时had turned。Her parents eventually admitted that to their relief,their daughter had turned into an adult.

correct 英[kəˈrekt] 美[kəˈrɛkt] adj. 正确的; 合适的; 符合公认准则的; 得体的; v. 改正; 批改; 指出错误; [例句]The correct answers can be found at the bottom of page 8正确答案在第8页末尾。[其他] 第三人称单数：corrects 现在分词：correcting 过去式：corrected过去分词：corrected

不正确，应是did you know it before，用过去时祝楼主更上一层楼