不便
inconvenient; inappropriate; unsuitable; short of cash
不变
constant; unvarying; (math.) invariant
不变价格
fixed price; constant price
不变量
invariant quantity; invariant (math.)
不辨菽麦
lit. cannot tell beans from wheat (idiom); fig. ignorant of practical matters
善者不辩,辩者不善
Good words are not persuasive, persuasive words are not good (idiom, from Laozi 老子 81). Do not be taken in by appearances.