An effective method to generate a large number of parallel sentences for training improved neural machine translation (NMT) systems is the use of  back-translations of the target-side monolingual data.
<fluency> An effective method to generate a large number of parallel sentences for training improved neural machine translation (NMT) systems is the use of  back-translations of the target-side monolingual data.
An effective method to generate a large number of parallel sentences for training improved neural machine translation (NMT) systems is the use of the back-translations of the target-side monolingual data.