R04的中频信号到射频信号的调制是由()完成的。
A.RIIC
B.RTRB
C.RLPB
D.RFIL
参考答案:B
________ the book if you are free, and you will learn a lot about how to study English.
A.Read
B.Having read
C.To read
D.Reading
住宅内插座,低于( )时,应采用安全型插座且配电回路设有漏电电流动作保护装置时,其安装高度可不受限制。
A.0.3m
B.1.5m
C.1.8m
D.2.3m