Tks @harmonyliu, its works for me. U save my day.

I think there is some dependency bug in the source code (version azure-storage-blob==2.1.0 ) of blockblobservice.py and __init__.py under site-packages/azure/storage/blob/ directory. Because when I type in
`from azure.storage.blob.blockblobservice import BlockBlobService`
it worked.

_Originally posted by @harmonyliu in https://github.com/Azure/azure-storage-python/issues/389#issuecomment-595476178_

Start by reproducing the import with azure-storage-blob==2.1.0 and inspect the mentioned blockblobservice.py and __init__.py files under azure/storage/blob/. Compare the failing import with the working blockblobservice import described in the issue; done means the dependency or source discrepancy is identified and the intended import behavior is clear.

Written by the indexing model from the issue text.