A transmission at least comprising: a first shaft; a second shaft; a third shaft; and a fourth shaft; wherein the first, second, third, and fourth shafts(11,12,13,14) are parallel to each other; wherein the first shaft includes a first gear and a second gear, the first gear coupling to the first shaft, the second gear coupling to or idling around the first shaft when a first clutch is switched; wherein the second shaft includes a third gear and a fourth gear, the third gear meshing with the first gear and coupling to the second shaft, the fourth gear coupling to or idling around the second shaft when a second clutch is switched; wherein the third shaft includes a sixth gear and a seventh gear, the sixth gear meshing with the first gear and coupling to the third shaft, the seventh gear coupling to or idling around the third shaft when a fourth clutch is switched; and wherein the fourth shaft includes a ninth gear, the ninth gear meshing with the second gear, the fourth gear, and the seventh gear, and coupling to the fourth shaft, characterized in that the transmission further comprises: a fifth shaft that is parallel to the fourth shaft; wherein the fourth shaft includes an eleventh gear and a twelfth gear, the eleventh gear coupling to the fourth shaft, the twelfth gear coupling to or idling around the fourth shaft when a sixth clutch is switched; and wherein the fifth shaft includes a fourteenth gear and an eighteenth gear, the fourteenth gear meshing with the twelfth gear and coupling to the fifth shaft, the eighteenth gear meshing with the eleventh gear, and coupling to or idling around the fifth shaft when an eighth clutch is switched. a first shaft; a second shaft; a third shaft; and a fourth shaft; wherein the first, second, third, and fourth shafts(11,12,13,14) are parallel to each other; wherein the first shaft includes a first gear and a second gear, the first gear coupling to the first shaft, the second gear coupling to or idling around the first shaft when a first clutch is switched; wherein the second shaft includes a third gear and a fourth gear, the third gear meshing with the first gear and coupling to the second shaft, the fourth gear coupling to or idling around the second shaft when a second clutch is switched; wherein the third shaft includes a sixth gear and a seventh gear, the sixth gear meshing with the first gear and coupling to the third shaft, the seventh gear coupling to or idling around the third shaft when a fourth clutch is switched; and wherein the fourth shaft includes a ninth gear, the ninth gear meshing with the second gear, the fourth gear, and the seventh gear, and coupling to the fourth shaft, characterized in that the transmission further comprises: a fifth shaft that is parallel to the fourth shaft; wherein the fourth shaft includes an eleventh gear and a twelfth gear, the eleventh gear coupling to the fourth shaft, the twelfth gear coupling to or idling around the fourth shaft when a sixth clutch is switched; and wherein the fifth shaft includes a fourteenth gear and an eighteenth gear, the fourteenth gear meshing with the twelfth gear and coupling to the fifth shaft, the eighteenth gear meshing with the eleventh gear, and coupling to or idling around the fifth shaft when an eighth clutch is switched. a fifth shaft that is parallel to the fourth shaft; wherein the fourth shaft includes an eleventh gear and a twelfth gear, the eleventh gear coupling to the fourth shaft, the twelfth gear coupling to or idling around the fourth shaft when a sixth clutch is switched; and wherein the fifth shaft includes a fourteenth gear and an eighteenth gear, the fourteenth gear meshing with the twelfth gear and coupling to the fifth shaft, the eighteenth gear meshing with the eleventh gear, and coupling to or idling around the fifth shaft when an eighth clutch is switched.