Open Access
表1
任务难度
| 难度等级 | 描述 |
| 简单(Ⅰ级) | 信息提示灯工作并通过颜色指明危险信息类型 |
| 中等(Ⅱ级) | 信息提示灯工作但不指明危险信息类型 |
| 困难(Ⅲ级) | 信息提示灯不工作 |
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