In addition, shared features generally portray common information between the two sub-tasks, like semantic and syntactic information, which also exist in other NLP tasks.
the prevalent model of Bidirectional Encoder Representations from Transformers (BERT) (Devlin et al., 2018), which is a pre-trained bidirectional Transformer encoder that achieves state-of-the-art performances across a variety of NLP tasks, is chosen as the shared network.