A.无线 B.有线 C.先有线，后无线 D.先无线，后有线
A.114.8Hz+186.2Hz B.115.8Hz+186.2Hz C.116.8Hz+186.2Hz D.115.8Hz+188.2Hz
A.零 B.无穷大 C.约几千欧
A.123.0HZ B.186.2HZ C.131.8HZ D.114.8HZ
A.1 B.2 C.3 D.4
