说明：  设计一个两位二进制数大小比较器。要求当二进制数A=A1A0大于二进制数B=B1B0时，电路输出为1，否则为0（A1，A0，B1，B0用四个脉冲源代替），建立仿真模型并保存。
(Design a two binary magnitude comparator. Required when the binary number is greater than the binary number A = A1A0 B = B1B0, the circuit output is 1, otherwise 0 (A1, A0, B1, B0 in place with four pulse sources), and save the simulation model.)