以下关于黑变病的描述错误的是（）。
A.多累及成年人
B.网状排列的色素沉着斑
C.皮损境界清楚
D.自觉症状不明显
E.女性较男性多
参考答案：C
漏电保护器的使用是防止（）
A.触电事故
B.电压波动
C.电荷超负荷
— It's reported that the new underground line has been completed.
— Yes, but it hasn't been made clear _____ it's to be opened to traffic. [ ]
A. that
B. who
C. what
D. when
