| 等级 Grade | 计算公式 Computational formula | 分级标准 Grading standard |
|---|---|---|
| 1 | x-2δ | <x-2δ |
| 2 | (x-2δ)+0.5δ | x-2δ—(x-2δ)+0.5δ |
| 3 | (x-2δ)+2×0.5δ | (x-2δ)+0.5δ—(x-2δ)+2×0.5δ |
| 4 | (x-2δ)+3×0.5δ | (x-2δ)+2×0.5δ—(x-2δ)+3×0.5δ |
| 5 | (x-2δ)+4×0.5δ | (x-2δ)+3×0.5δ—(x-2δ)+4×0.5δ |
| 6 | (x-2δ)+5×0.5δ | (x-2δ)+4×0.5δ—(x-2δ)+5×0.5δ |
| 7 | (x-2δ)+6×0.5δ | (x-2δ)+5×0.5δ—(x-2δ)+6×0.5δ |
| 8 | (x-2δ)+7×0.5δ | (x-2δ)+6×0.5δ—(x-2δ)+7×0.5δ |
| 9 | (x-2δ)+8×0.5δ | (x-2δ)+7×0.5δ—(x-2δ)+8×0.5δ |
| 10 | x+2δ | >x+2δ |
