A.YD梢徑-桿長(zhǎng)-容許彎矩 B.YD桿長(zhǎng)-梢徑-容許彎矩 C.YD容許彎矩-梢徑-桿長(zhǎng) D.YD桿長(zhǎng)-容許彎矩-梢徑
A.-14 B.-16 C.-18 D.-20
A.3 B.4 C.5 D.6