固然…但是 / 固然…也【gùrán … dànshì / gùrán … yě】

固然 grants a fact, "admittedly, of course", and the clause after it turns with 但是, 可是 or 却 to the point that weighs more. 固然 sits after the subject, before the predicate. It is a little formal but is heard in serious conversation as well as written.

The weight always falls on the second clause. The 固然 clause is the point the speaker accepts but sets aside.

固然…也: both are fine

With 也 instead of a turn, 固然 says the first option is good and the second is acceptable too. 虽然 can't be swapped in here.

诚然 does the same conceding job in formal argument, almost always followed by 然而.

Facts, not hypotheses

固然 concedes something true. For "even if" about something that may not happen, use 即使 or 就算.

• × 固然下雨，我也去 → 即使下雨，我也去