I'm pretty sure opera can be sung in any language.
Italian 2nd answer The most common are Italian, French, German, Russian and English, but there are operas in many other languages too. Opera is an art-form, and it can be written in any language the...
German.
Puccini composed La Boheme.
The libretto (lyrics) are often in Italian - but they can be in any language. Other languages that are often used are German and French.