Against the backdrop of the COVID-19 outbreak, an emergency policy initiative called “Suspending Classes Without Stopping Learning” was launched by the Chinese government to continue teaching activities as schools across the country were closed to contain the virus. However, there is ambiguity and disagreement about what to teach, how to teach, the workload of teachers and students, the teaching environment, and the implications for education equity. Possible difficulties that the policy faces include: the weakness of the online teaching infrastructure, the inexperience of teachers (including unequal learning outcomes caused by teachers’ varied experience), the information gap, the complex environment at home, and so forth. To tackle the problems, we suggest that the government needs to further promote the construction of the educational information superhighway, consider equipping teachers and students with standardized home-based teaching/learning equipment, conduct online teacher training, include the development of massive online education in the national strategic plan, and support academic research into online education, especially education to help students with online learning difficulties.

Ischemia reperfusion (I/R) injuries occurred in many pathological and surgical processes (e.g. thrombolytic therapy, organ transplantation, aortic cross-clamping, coronary angioplasty and cardiopulmonary bypass) and harmed multiple organs and tissues. Vitamin D is a well-known sterol hormone and a nutritional ingredient able to promote the deposit of calcium and regulate phosphorus metabolism in the body. In addition, vitamin D has therapeutic effects on some diseases (e.g. cardiovascular disease, diabetes, cancer, neurological diseases, multiple sclerosis and inflammation). Studies showed that vitamin D3 was closely related with I/R injury occurrences in heart, brain, spine, liver, kidney, and ovary. The literature searching was conducted in PubMed, Embase, Cochrane Library, Web of Science, and SCOPUS from inception to 20 September 2021. Data showed that supplements with vitamin D₃ can remarkably attenuate I/R injuries. This paper reviewed recent progresses of vitamin D₃ preventing I/R injuries in clinical investigations and animal tests to enlighten future studies.