6 sentences

1. 你是我的朋友，我的知己。

   nǐ shì wǒ de péng​you, wǒ de zhī​jǐ.

   You're my friend, my confidant.

   Source: OpenSubtitles

2. 海内存知己，天涯若比邻。

   hǎi​nèi cún zhī​jǐ, tiān​yá ruò bǐ​lín.

   A bosom friend afar brings a distant land near.

   Source: Dong Chinese Dictionary

3. 人生得一知己足矣，他就是我最亲近的朋。

   rén​shēng dé yī zhī​jǐ zú yǐ, tā jiù shì wǒ zuì qīn​jìn de péng.

   To have one soulmate in life is enough; he is my closest friend.

   Source: Dong Chinese Dictionary

4. 知己知彼，百战不殆。

   zhī​jǐ zhī bǐ, bǎi​zhàn​bù​dài.

   Know yourself and know your enemy, and you will never be defeated in a hundred battles.

   Source: Dong Chinese Dictionary

5. 知彼知己，方能百战不殆。

   zhī bǐ zhī​jǐ, fāng néng bǎi​zhàn​bù​dài.

   Know yourself and know your enemy, and you will never be defeated.

   Source: Dong Chinese Dictionary

6. 他们二人意气相投，彼此十分知己。

   tā​men èr rén yì​qì​xiāng​tóu, bǐ​cǐ shí​fēn zhī​jǐ.

   The two of them share similar interests and are very close friends.

   Source: Dong Chinese Dictionary