Theory must be based on practice.

理论必须以实践为基础。以实践为基础。

youdao

Theory must be based on practice.

理论必须以实践为基础。

youdao

Theory study must be based on practice and service for practice.

理论研究工作必须立足于实践，并为实践服务。

youdao

Theory study must be based on practice and service for practice.

理论研究工作必须立足于实践，并为实践服务。

youdao