多谢回答! Hulululu and Piang老师. Just to clarify one thing - Piang老师

Just read your blog, thanks a lot for your reply! Just want to clarify one thing:

My parents can change their passports in China before they come to U.S., and there should be a problem if they bring both 老护照(with valid B2 visa) and 新护照入境. Your blog used example for people live in U.S. and travel to China and back to U.S., this should be the same situation as my parents. Is it correct?

Thanks again!