Question: what language pairs are explored?
Answer: De-En, En-Fr, Fr-En, En-Es, Ro-En, En-De, Ar-En, En-Ru
Alternative answer: French-English-Spanish (Fr-En-Es), German-English-French (De-En-Fr) and Romanian-English-German (Ro-En-De), Arabic (Ar), Spanish (Es), and Russian (Ru), and mutual translation between themselves constitutes six zero-shot translation