二重复句1：单句+复句；复句+单句

There are two orders — (a) Simple sentence + Compound sentence: e.g. 我决定去中国留学 (simple sentence) ｜ 即使中文再难我也要去学 (a concessive compound sentence with the pair 即使……也……, even if...still...). (b) Compound sentence + Simple sentence: e.g. 因为生病所以我没去上课 (a cause-and-effect compound sentence 因为……所以……) ｜ 没想到的是老师一下课就来看我了 (simple sentence). Together they form one long sentence with two layers of relationship.

When you need to express multiple layers of meaning (cause-and-effect, concession, and contrast at once) in one long sentence, often found in written usage or narrative with complex logic.

Vietnamese learners often leave out one half of a conjunction pair (writing 即使 but forgetting 也, or 虽然 but forgetting 但), making the sentence clumsy. You must keep the full pair: 即使……也……, 因为……所以……, 虽然……但……. In addition, commas must clearly separate the clauses so the reader can see each layer of relationship.