a. not solved
a. 未解释的, 未解决的
1. The mystery of the missing painting remains unsolved.
消失的画作之谜仍然没有解决。
2. Many unsolved cases still haunt the police department.
许多未解决的案件仍然困扰着警察局。
3. She is determined to find answers to the unsolved questions in her research.
她决心在自己的研究中找到未解的问题的答案。