unsuspected

a. 未知的

Articles in Time's Medical Section often alert readers to unsuspected ailments.

《时代》周刊医药栏目里的文章常告诫读者对自己意想不到的疾病保持警惕。

As the project develop, unsuspected difficulty come to the fore.

随著工程项目的发展，没有料到的困难接连出现了。