Answer:

If you are walking down the street and notice that a stranger has dropped a notebook or something, you want to call their attention to the fact, but of course you cannot call their name. You can call out, “Sir (Ma’am, Miss), you dropped your notebook.” Or you might simply call out in an appropriately loud voice, “Excuse me! You dropped your notebook.” When words fail you, you can pick up the dropped object, run after the person, tap him or her on the shoulder and hand over the object.