两个正方体的棱长比是2:3,体积比是( )。
8:27
In remote mountainous villages in China, it is not ______ to find families with men wearing thick
moustache, shabby clothes and worn shoes, chewing tobaccos and with porridge as their main
daily food. [ ]
A. rare
B. seldom
C. ordinary
D. hardly
对地电压低于()为安全电压。