回复：请教：到上海再转机的话，可以买到打折票吗？

A lot of people may now know if you book a r/t trip from North America to certain cities in China, you can have chance to fly free on a domectic portion in China, provided you flight China based airlines(MU,CA etc.) For example, if your destination is Shanghai, but you want to stay in Beijing for a few days before you reach Shanghai, the Beijing->Shanghai portion is free. This could be considered obvious, but if your final destination in China is Hangzhou, you can book North America<->Beijing->Hangzhou Shanghai->North America, Beijing->Hangzhou portion is also free.
One of my friend recently did MU LAX->PVG->ShenZhen
PVG->LAX, the PVG->ShenZhen is free. The reason is simple, airlines want your business to fill their empty seats, while make money on your international portion of the bookings.
Always ask your travel agent when booking, a lot of inexperience agnets may not know well about this trick.