Hunny it’s self explanatory it tells you exactly what you need to do
No looking at his watch is not a complete thought because it doesn't have a subject
Answer:
In most contexts, they are interchangeable. The only difference that most native speakers can agree upon is that someone is more formal than somebody (just as anyone is more formal than anybody, and everyone is more formal than everybody).
Jane will borrow some books, if she goes to the library.
hope this helped. So sorry if it is incorrect!
