单项选择题
A.6666.7 B.13333.3 C.333.33 D.666.67
A.bh3/12 B.bh3/6 C.bh2/12 D.bh2/6
A.1 B.2 C.3 D.4
A.离左支点L/4处 B.离左支点L/2处 C.离左支点3L/4处 D.离左支点L/3处
微信扫一扫,加关注免费搜题