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_

首先使用 azure-storage-blob==2.1.0 复现 import，并检查 azure/storage/blob/ 下提到的 blockblobservice.py 和 __init__.py 文件。将失败的 import 与 issue 中描述的可正常工作的 blockblobservice import 进行比较；当确定依赖项或源代码的差异，并明确预期的 import 行为后，即表示完成。

由索引模型根据 Issue 内容生成。