Thank you for the help. But I still don't quite catch the last sentence. "Shanghai is [to the] SSE of Beijing". What does that "SSE" indicate? Is this sentence also correct?
What if the two city or province share the same border? Is it OK to use A is to the east of B?
Yes.
St Paul is [to the] east of Minneapolis, Minnesota.
Tokyo is [to the] east of Yokohama (just).