a. not clear to the mind
a. 不易了解的, 不清楚的, 含混的
1. The instructions were unclear, so I asked for help.
说明不清楚，所以我请求帮助。
2. His reasons for leaving the job were unclear to everyone.
他离开工作的理由对大家来说都不清楚。
3. The map was unclear, making it hard to find the location.
地图不清晰，这让找到位置变得困难。