must/mustn't表达用电规则 — 英语选择题
题目
在家中用电时，下列哪句话正确表达了安全用电规则？
A. You mustn't touch electrical wires with wet hands.
B. You must touch electrical wires with wet hands.
C. You mustn't turn off the lights when you leave.
D. You must put a metal fork into the toaster.