2 sentences for 界线 (jiè​xiàn — limits)

1. 你很擅长划清界线啊。

   nǐ hěn shàn​cháng huà​qīng jiè​xiàn a.

   You're good at drawing boundaries.

   Source: OpenSubtitles

2. 你的行为已经超出了道德界线。

   nǐ de xíng​wéi yǐ​jīng chāo​chū le dào​dé jiè​xiàn.

   Your behavior has already crossed the moral line.

   Source: Dong Chinese Dictionary