_____ all the boys in his class, Tom is the shortest[ ]
A. In
B. For
C. From
D. Of
答案:D
数据流程图是分层次的,绘制时采取()逐层分解的办法.
A.从下到上
B.从左到右
C.从前到后
D.自顶向下
对500kV线路及重要电源线,防雷保护角有何规定?