代码：

//反相器
`timescale 1ns/10ps
module inv(
A,y);
input A;
output y;
assign y=~A;
endmodule
//testbench
module inv_tb;

reg A;
wire YY;

inv inv(
		.A(A),
		.y(YY)
		);
		
initial begin
		A<=0;
	#10 A<=1;
	#10 A<=0;	
	#10 A<=1;
	#10 A<=0;	
	#10 A<=1;
	#10 A<=0;	
	#10 $stop;
end

endmodule

实验波形：