2 sentences

1. 这种新型抗生素是耐药菌的克星。

   zhè zhǒng xīn​xíng kàng​shēng​sù shì nài yào jūn de kè​xīng.

   This new antibiotic is the nemesis of drug-resistant bacteria.

   Source: Dong Chinese Dictionary

2. 迷信的人认为他命中注定是那个人的克星。

   mí​xìn de rén rèn​wéi tā mìng zhōng zhù​dìng shì nà gè rén de kè​xīng.

   Superstitious people believe he is destined to be that person's nemesis.

   Source: Dong Chinese Dictionary