Without knowing what your shoes look like it is tough to say. If the all black tennis shoe does not look too much like an athletic shoe you should be fine. Think of the type of shoes nurses wear. The other shoes should also be fine if they are neutral and not flashy.
Black flats
What else are you wearing & what specific job are you doing? Dress appropriately & comfortably for the position. Make sure whatever you choose is comfortable since you'll likely be on your feet all day!
All black flats
All black flat
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