before_sent:  In this paper , we propose UniViLM : a Unified Video and Language pre-training Model for both multimodal understanding and generation.
before_sent_with_intent: <fluency>  In this paper , we propose UniViLM : a Unified Video and Language pre-training Model for both multimodal understanding and generation.
after_sent:  In this paper , we propose UniViLM : a Unified Video and Language pre-training model for both multimodal understanding and generation.