中文摘要：

证明顶点数为n≥3，弧数为m≥（n 2）＋2的强连通有向图。中存在两个不同的顶点u，v，使得D-u和D-v。都是强连通的；并用例子说明这里所给的关于弧数的下界是紧的．

英文摘要：

It is proved that a strongly connected digraph D with n≥3 vertices and at least（n 2）＋2 arcs has two distinct vertices u＊ , v＊ such that both D--u＊ and D--v＊ are strongly connected, and the examples show that the above lower bound on the number of arcs is sharp.