- 疑难杂症 yínánzázhèng hard casescomplicated problems or difficult situations that are hard to resolve or handle
- 疑难解答 yínánjiědá q&athe process of providing answers or solutions to difficult questions or complex problems, often in an academic or advisory setting
- 疑难问题 yínánwèntí knotty problema complex or difficult problem that is hard to resolve or understand
