what does 上疾 mean in this sentence (她在网球场上疾如闪电。)
她在网球场上疾如闪电。She is fast as lightning on the tennis court.
上疾 here isn't a word; it's just 上 and 疾 happening to meet at the word boundary.
在……上 is the structure to mean &quot;on&quot; in this sentence.
疾如闪电 is a more literary way of saying 快得像闪电. &quot;疾&quot; has the archaic meaning of &quot;fast; quick&quot;, which is rather unproductive in forming phrases and words nowadays, but you can still see it in phrases e.g. 疾如闪电, 迅疾 (a literary way of saying &quot;fast, rapid&quot;), 不疾不徐 (unhurried, unhurriedly; lit. not fast (and) not slow) or 眼疾手快 (agile; lit. quick eyes and quick hands).