[Django]-Django official tutorial for the absolute beginner, absolutely failed!

You overlooked this paragraph in the 4. part of the tutorial:

In previous parts of the tutorial, the templates have been provided with a context that contains the poll and latest_poll_list context variables. However, the generic views provide the variables object and object_list as context. Therefore, you need to change your templates to match the new context variables. Go through your templates, and modify any reference to latest_poll_list to object_list, and change any reference to poll to object.