【简答题】Researchers at San Diego Zoo have been studying what has been described as the “secret language” of elephants. They have been monitoring(监测) communications between animals that cannot be heard by huma...
【单选题】In the design of a radio receiver containing a type 3 filter, a low capacitance level and a high inductance level would be most useful for the purpose of:
A.
enhancing radio reception across the frequency spectrum.
B.
tuning out signals at high and low frequencies.
C.
tuning in a radio station at a fixed frequency.
D.
minimizing unwanted audio noise at middle frequencies.