A:①②
B:②③
C:③④
D:①④
A、B是两个完全相同的电热器,A通以图甲的方波交变电流,B通以图乙所示的正弦交变电流,则两电热器的电功率PA:PB等于( )
— Do you know the man over there?
—Yes. He is Mr Yang, a celebrated reporter.