When and where to go for the on-salary holiday ___________ yet.
A:are not decided
B:have not been decided
C:is not being decided
D:has not been decided
图片主要说明( )
计算:等于( )
用遥控器调换电视机的频道的过程,实际上就是传感器把光信号转化为电信号的过程。下列属于这类传感器的是( )