我按照教程一步一步的来,先注释掉blacklist i2c-bcm2708,然后在加上i2c-dev,下面在执行sudo apt-get update的时候就显示404 not found呢,我网络应该是好的,可以ping通。sudo apt-get install i2c-tools 的时候,显示install these packages without verification,选择yes,还是显示404 not found。后面输入sudo adduser pi i2c 显示'the group 'i2c' does not exist',无法打开i2c,求大神指教,多谢!