Before revision:  Evaluated on three domains of German-to-English translation task with no supervised data, this simple technique alone (without any out-of-domain parallel data) can already surpass all previous domain adaptation methods---up to + 9.48 BLEU over the strongest previous method , and up to +27.77 BLEU over the unadapted baseline. Moreover, given available supervised out-of-domain data on German-to-English and Romanian-to-English language pairs, we can further enhance the performance and obtain up to + 19.31 BLEU improvement over the strongest baseline, and +47.69 BLEU increment against the unadapted model .
After revision:  Evaluated on three domains of German-to-English translation task with no supervised data, this simple technique alone (without any out-of-domain parallel data) can already surpass all previous domain adaptation methods---up to + 19.31 BLEU improvement over the strongest baseline, and +47.69 BLEU increment against the unadapted model .