Simplify the following text for a Grade 11 native English-speaking person.
Original: Some composers , such as Mikhail Glinka , Alexander Serov , Rimsky-Korsakov , Puccini , and Mascagni wrote passages of music without text and subsequently had the librettist add words to the vocal melody lines .
Simplified: Composers , such as Mikhail Glinka , Alexander Serov , Rimsky-Korsakov , Puccini , and Mascagni all did this sometimes .