Use the pre-trained model to make new predictions

I'm using the pre-trained model to get predictions for new questions on SQUAD dataset.

For a paragraph of an article, I add questions that aren't necesarely answerable by the paragraph. Nonethless, the model in the pre-process asks me to insert the `answer_start` which I cannot provide since I don't know if the answer for the question is in the paragraph.

Is there a way to get the predictions (and not an error which let the model produce a default output) without inserting the real `answer_start` value?

I look forward to hearing from you. Thank you :)
Cristina