固然…但…: admittedly…, but…
复句 / complex sentences
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
固然 ("admittedly, it's true that") acknowledges a first point before raising a second, usually more important. It's the basic tool of nuanced argument: "Granted A, but B".
固然 goes after the subject. The second part starts with 但(是)/可是/然而, often with 也: 成绩固然重要，但健康也很重要.
Versus 虽然: 虽然 concedes a fact; 固然 grants an argument while putting it in perspective.
Examples
考试成绩固然重要，但能力更重要。
Kǎoshì chéngjì gùrán zhòngyào, dàn nénglì gèng zhòngyào.Exam results matter, admittedly, but ability matters more.
出国留学固然能开阔眼界，可是费用也很高。
Chū guó liúxué gùrán néng kāikuò yǎnjiè, kěshì fèiyong yě hěn gāo.Studying abroad broadens your horizons, sure, but it's also very expensive.
你的想法固然好，但是很难实现。
Nǐ de xiǎngfǎ gùrán hǎo, dànshì hěn nán shíxiàn.Your idea is good, granted, but hard to carry out.
Common mistakes
✗ 固然考试重要 → ✓ 考试固然重要 (固然 after the subject).
✗ 固然 with no second part: it always announces a "but".