|123......1 ||2E2 3E2 4E2...... 1991E2 1992E2 　｜ |3E3 4E3 5E3...... 1992E3 1992E3 ||. ||. ||. ||. ||................................................||..........1991E1990.............................||1991E1 E1 E1991..........1992E1991|