单选题图（a）滤波器的幅频特性如图（b）所示，当<br/> <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23827649_0.png">时，输出uo＝uo1，当<br/> <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23827649_0_1.png"><br/> 时，输出uo＝uo2，那么，可以算出（　　）。<br/> <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23827649_0_2.png"><br/> 图（a）<br/> <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23827649_0_3.png"><br/> 图（b）<br/> <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23827649_0_4.png">