警方怀疑有内鬼秘密渗透进了犯罪团伙。

The police suspected that a mole had ___infiltrated the criminal organization secretly.

咖啡渍慢慢渗入了桌布，留下了一个棕色的印记。

The coffee stain gradually ___infiltrated the tablecloth, leaving a brown mark.

这项计划旨在将环保意识逐步渗透到学校教育中。

The program seeks to ___infiltrate environmental awareness into school education gradually.