rarer

The rarer it is, the more it is worth.

物以稀为贵。

Lines composed primarily of anapestic feet, often with an additional unstressed syllable the end of the first line, are much rarer in English verse.

各行基本由仄仄平音所成，第一行结尾经常附加一非重读音节，英语韵文，罕见行。