shì qíng / suī rán / fù zá / dàn / jiǔ jiǔ guī yī / hé xīn / wèn tí / zhǐ yǒu / yí gè

事情虽然复杂，但九九归一，核心问题只有一个。

Although the matter is complicated, when all is said and done, there is only one core issue.