How do you plan to solve it?
module t_ff_async_pr ( input CLK, input RST, input PRE, input T, output reg Q ); always @(posedge CLK or posedge RST or posedge PRE) begin if(RST) Q<=1'b0; else if(PRE) Q<=1'b1; else if(T) Q <= ~Q; else Q<=Q; end endmodule