English parallel structure refers to a conjunction connecting two equivalent words and equivalent structure.

The coordinate conjunctions and, but, and, or, else, both … and, or … or, there … or, not only … but (also) can connect two equivalent words and equivalent structures.

Duality refers to a rhetorical way: two sentences with the same number of words and similar structure express related or opposite meanings, or two symmetrical sentences are used to enhance the language effect (such as "writing a thousand words, digressing Wan Li"). Many poems have duality.

English also has duality. We English majors study literature in class, and many articles in English literature also have duality.