Is there a difference between "Mănânc usturoii DE PE masă" and "Mănânc usturoii PE masă"? Those "two prepositions"-phrases are one of the themes that confound me the most in Romanian! :(
When you say "Eu mănânc usturoii de pe masă" you are saying that you are eating those garlic(s) that are on the table (hence - off of the table). Sayin "PE masă" alone would be understood as "I eat the garlic(s) while I am sitting or standing on the table.
Edit: I realised the accepted and best answers had been wrong, so I modified the answers for this sentence.
Substantivul ”usturoi” nu are plural! Corect este: ”Eu mănânc usturoiul de pe masă.”