換気扇穴あけ作業(内壁) https://www.tyoukoku.com/blog/blog/2014/08/30/%e6%8f%9b%e6%b0%97%e6%89%87%e7%a9%b4%e3%81%82%e3%81%91%e4%bd%9c%e6%a5%ad%ef%bc%88%e5%86%85%e5%a3%81%ef%bc%89/