(c) Pretraining on SQuAD and SQuAD-T with finetuning (fourth and fifth row) significantly outperforms (by more than 5%) the highest-rank systems on WikiQA.
topWe see high correspondence between same word from question and context such as senator and john, in SQuAD-pretrained model, but the SQuAD-tpretrained model fails to learn such correspondence.