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Customs and Immigration - understanding the questions
I follow several travel vloggers - people who travel professionally and post youtube videos. One of them is the Portable Professional who has a ton of useful videos. She recently posted one about the questions you get asked going thru Custom and Immigration at airports. Does a good job of explaining why they ask what they do and the best way to answer. I've provided a link below of you can do a google search of "portable airport questions" and probably get the link. She includes a downloadable ebook with more info.
https://www.youtube.com/watch?v=mWqdZZpPdFA2