LC组成并联谐振回路，谐振频率<img src="https://nimg.ppkao.com/2019-05/leiyawen/2019051715135565926.jpg?sign=2eec688c0f4598e7886bd4e8407bfeec&t=62d5d2c5" />把它串接在电路中，就能阻止频率为（）的信号通过。<br /> <img src="https://nimg.ppkao.com/2019-05/leiyawen/2019051715134499975.jpg?sign=03590482e142281bfad634b151bcdbff&t=62d5d2c5" />