Compounds of 乙

• 甲の薬は乙の毒
  (exp) One man's meat is another man's poison
  lit: one's medicine is another's poison
• 甲乙つけがたい
  (exp) it is difficult to say which of the two is better
• 甲乙付けがたい
  (exp) it is difficult to say which of the two is better