I am a student studying in Ningbo, Zhejiang Province, China on a single entry student visa.

This Summer I'll be travelling outside China (Cambodia, Vietnam etc.) and have a return flight home to UK booked from Shanghai at the end. I want to leave bags and books in Ningbo while travelling so could I fly from some South East Asian country e.g. Cambodia into Ningbo (in Zhejiang), get my things, get a train to Shanghai and fly home from there? As long as I keep the landing in Ningbo to leaving Shanghai under 144 hours?