Nominal sentences in Literary Chinese
The most common way to say “[A] is [B]” or “[A] is a type of [B]” in Literary Chinese is to use a nominal sentence. This has no copula (verb expressing being) but instead puts the two items next to each other, followed by 也 (yě).
The structure is simple:
[A] [B] 也
If the subject is already known, or is obvious, it can be omitted. For example:
商之所短也 (shāng zhī suǒ duǎn yě) [shang - ‘s - that which is - inadequate - ye]
“(That)* is* what I, Lord Shang, would find inadequate”
In this sentence, the subject is omitted, as it references something that has just been mentioned. Using “that” is a possible translation.
In early Classical Chinese texts, the copula is almost always omitted. In later texts a copula may be used and 也 may be omitted.
Negation
The character 非 (fēi) is normally used to negate a nominal sentence:
[A] 非 [B] 也
or, omitting 也:
[A] 非 [B]
The most famous example of this is probably the first line of the Dao De Jing:
道可道非常道 (dào kě dào fēi cháng dào) [Way - can - Way - not - eternal - Way]
"The Dao that can be named is not the eternal Dao"
Remember that 也 is also used as a general marker for the end of a sentence or phrase; not all sentences ending with 也 are nominal sentences.