two successive letters (especially two letters used to represent a single sound: `sh\\\' in `shoe\\\')
造句
Digraphs have a simple pictorial representation. 有向圖有簡(jiǎn)單的圖形表示。
Using matrix theory, we present a sharp upper bound on the spectral radius of digraphs and strongly connected diagraphs. 摘要利用矩陣?yán)碚?，給出了簡(jiǎn)單有向圖的譜半徑可達(dá)上界和強(qiáng)連通有向圖的譜半徑上界。