A.always@（posedge clk or negedge reset）begin if（!reset）current_state<=s0；else current_state<=next_state；end
B.always@（posedge clk ）begin if（!reset）current_state<=s0；else current_state<=next_state；end
C.always@（posedge clk t）if（reset）current_state<=s0；else current_state<=next_state
D.always@（posedge clk or negedge reset）if（reset）current_state<=s0；else current_state<=next_state

A.always@（posedge clk）case （state ）0：next_state<=1；1：next_state<=x
B.always@（posedge clk）case （state ）0：if（a==0）next_state<=1；else next_state<=x；1：next_state<=x
C.always@（posedge clk）case （state ）0：if（state==0）next_state<=1；else next_state<=x；1：next_state<=x
D.以上都不對(duì)