求翻译：腹板和一级或二级翼缘的截面分类为二级截面，参见5.5.2(11)，腹板压力区比例应当有20εtw靠近压力翼缘，另有20εtw靠近塑性中性轴，如图6.3是什么意思？

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Level 3, and level 2 or level wing leading edge cross-section of the classification of level 2 cross-section, see 5.5 2 (11) and abdominal pressure area ratio should be 20 TW epsilon close to pressure wing leading edge, and another 20 epsilon close to tw plastic neutral axis, such as figure 6.3

三级腹板和一级或二级翼缘的截面分类为二级截面，参见5.5.2(11)，腹板压力区比例应当有20εtw靠近压力翼缘，另有20εtw靠近塑性中性轴，如图6.3

Three-level Web and flange in a grade I or grade II classification of section II section, see 5.5.2 (11), pressure should be 20 per cent of the Web ε TW near the pressure flange, another 20 Epsilon TW near the plastic neutral axis, as shown in Figure 6.3

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