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I applied for a B1/B2 US visa to take the Usmle step 2 CS exam. But I was only given a pure B1 visa. It really surprised me coz taking an exam doesn't really fit the description of a business purpose at least based from the B1 visa definitions I've read. Or does it? So my question is if I go to US on a pure B1 to take the exam? Can I also say I plan to visit some friends after the exam while I am already there? Is that allowed?