Problems when I try to cvt my .csv file into conll2003 format

Hello everyone, I’m new here. I want to do a Chinese electronic medical records NER, but when I try to convert my .csv data file into conll2003 format, something happened.

dataset = load_dataset('csv',name='conll2003',data_files={'data.csv'})

I try to create a conll2003 format dataset using code above. It returns a dataset like below:

The values of ‘tokens’ and ‘ner’ should be type of list, but here they are string
If I did something wrong or maybe someone knows what should I do, please tell me. Many thanks!