解：??$(2) $??據已知條件可知：??$ A→B $??表示為??$ (+1$??，??$+3)$??，
??$B→C$??記為??$ (+2$??，??$0)$??，??$ C→D$??記為??$(+1$??，??$-2)$??，
∴該甲蟲走過的路線長為：??$ 1+3+2+1+2=9.$??
??$(3) $??若這只甲蟲從??$ A $??處去??$ P $??處的行走路線依次為
??$(+2$??，??$+2)$??，??$(+1$??，??$-1)$??，??$(-2$??，??$+3)$??，??$(-1$??，??$-2)$??，??$ P $??點位置如圖所示??$.$??
