three modules

You are given a module my_dff with two inputs and one output (that implements a D flip-flop). Instantiate three of them, then chain them together to make a shift register of length 3. The port needs to be connected to all instances. my_dffclk

The module provided to you is: module my_dff ( input clk, input d, output q );

Note that to make the internal connections, you will need to declare some wires. Be careful about naming your wires and module instances: the names must be unique.

Module shift - HDLBits (01xz.net)

module top_module ( input clk, input d, output q );
 wire q1,q2;
    my_dff my_dff1(
        .clk(clk),
        .d(d),
        .q(q1)
    );
   my_dff my_dff2(
        .clk(clk),
        .d(q1),
        .q(q2)
    );
    my_dff my_dff3(
        .clk(clk),
        .d(q2),
        .q(q)
    );
endmodule

wire的两个定义挺好的，值得思考，定义是必要的，但为什么自己思维固化了就没想到，程序写的也非常清晰

再写：

在这里不定义中间wire，也没法写对吧