3 sentences

1. 他的文章斐然成章，深受读者喜爱。

   tā de wén​zhāng fěi rán chéng​zhāng, shēn shòu dú​zhě xǐ'ài.

   His writing is brilliant and well-structured, making it very popular with readers.

   Source: Dong Chinese Dictionary

2. 斐是希腊字母表中的第21个字母。

   fěi shì Xī​là zì​mǔ​biǎo zhōng de dì21 gè zì​mǔ.

   Phi is the 21st letter of the Greek alphabet.

   Source: Dong Chinese Dictionary

3. “斐”这个字经常用来翻译外国的人名或地名。

   “ fěi” zhè​ge zì jīng​cháng yòng​lái fān​yì wài​guó de rén​míng huò dì​míng.

   The character 'Fei' is often used to transliterate foreign names and places.

   Source: Dong Chinese Dictionary