Question: who did the nationalists and communists in china form an alliance against
[{'answer': 'the Japanese', 'provenance': [{'wikipedia_id': '6627640', 'title': 'Second United Front', 'start_paragraph_id': 1, 'start_character': 145, 'end_paragraph_id': 1, 'end_character': 157, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '6627640', 'title': 'Second United Front', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 259, 'bleu_score': 0.9529077664391161, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5519173872742803018}, 'section': 'Section::::Abstract.'}]}]