Create a one-bit wide, 2-to-1 multiplexer. When sel=0, choose a. When sel=1, choose b.

译：

创建一个1位宽的2对1多路复用器。当sel=0时，选择a。当sel=1时，选择b。

个人解法：

module top_module( 
    input a, b, sel,
    output out ); 
    assign out = (sel==1)?b:a;
endmodule

官方解法：

module top_module (
	input a,
	input b,
	input sel,
	output out
);

	assign out = (sel & b) | (~sel & a);	// Mux expressed as AND and OR
	
	// Ternary operator is easier to read, especially if vectors are used:
	// assign out = sel ? b : a;
	
endmodule

运行结果：