例句與造句

1. The theory of graphs can be roughly partitioned into two branches : the areas of undirected graphs and directed graphs ( digraphs )
   圖論大致可分為兩個(gè)方向：無(wú)向圖與有向圖。
2. It's difficult to find directed graph (digraph) in a sentence. 用directed graph (digraph)造句挺難的