A．①→②→③→④→⑤→⑥→⑦                   B．②→④→③→①→⑤→⑦→⑥

C．③→②→④→⑤→①→⑦→⑥                   D．④→②→③→①→⑤→⑥→⑦

  • 答案
关闭