解决寄生通道干扰的有效方法是提高（）的频率选择性。解决组合频率干扰的有效方法是采用产生组合频率小的混频器电路。
参考答案：混频器之前电路
“It’s a long time since I enjoyed myself.” This sentence means______.
A．I enjoyed myself for a long time
B．I haven’t enjoyed myself for a long time
C．I want to enjoy myself
D．What a long time after I enjoyed myself
针对本案例，章某应该在前期进行可行性分析，请问可行性分析的基本内容有哪些？
