subdictionary

- * pg_catalog.english_stem is the subdictionary (here, a Snowball English stemmer) to use for thesaurus normalization.

english_stem 是用于知词典规范化子词典（这里我们用了一个 Snowball 英语词）。

- Specific stop words recognized by the subdictionary cannot be specified;

For example, assuming that a and the are stop words according to the subdictionary: + 被子词典别特定词是不能声明；