以下哪项是讨论编码本采用的方式？（）
A、指标法
B、马尔科夫法
C、专家会议
D、问卷法
参考答案：C
The old man used to live with his wife, but now he _____ alone after she died. [ ]
A. is used to live
B. gets used to living
C. used to live
D. is used for living
带煤气作业属于危险作业,应经过相关安全审批后方可作业。（）
