The word(s) "class" appears 3 time(s) in 3 verse(s) in Quran in Abdullah Yusuf Ali translation.

(1) To it are seven gates: for each of those gates is a (special) class (of sinners) assigned.

(سورة الحجر, Al-Hijr, Chapter #15, Verse #44)
(Arabic, Transliteration, Urdu (Ahmed Ali), Urdu (Jalandhry), Farsi, Yusuf Ali, Shakir, Picthal, Mohsin Khan, French, Spanish, Indonesian, Malay, German, Bosnian, Russian, Dutch, Italian, Portuguese, Tafsir - Jalal ad-Din, Tafsir - King Fahad Quran Complex)

(2) Strain not thine eyes. (Wistfully) at what We have bestowed on certain classes of them, nor grieve over them: but lower thy wing (in gentleness) to the believers.

(سورة الحجر, Al-Hijr, Chapter #15, Verse #88)
(Arabic, Transliteration, Urdu (Ahmed Ali), Urdu (Jalandhry), Farsi, Yusuf Ali, Shakir, Picthal, Mohsin Khan, French, Spanish, Indonesian, Malay, German, Bosnian, Russian, Dutch, Italian, Portuguese, Tafsir - Jalal ad-Din, Tafsir - King Fahad Quran Complex)

(3) And ye shall be sorted out into three classes.

(سورة الواقعة, Al-Waaqia, Chapter #56, Verse #7)
(Arabic, Transliteration, Urdu (Ahmed Ali), Urdu (Jalandhry), Farsi, Yusuf Ali, Shakir, Picthal, Mohsin Khan, French, Spanish, Indonesian, Malay, German, Bosnian, Russian, Dutch, Italian, Portuguese, Tafsir - Jalal ad-Din, Tafsir - King Fahad Quran Complex)