abbr.efficiency 效率；equivalent focal length 等效焦距；expectant father 准爸爸；experimental flight 试飞 英英释义： EfEf (Ф ф; italics: Ф ф) is a Cyrillic letter, commonly representing the voiceless labiodental fricative , like the pronunciation of ⟨f⟩ in "fill". The Cyril