Is it correct to say "Two soldiers are standing guard on the top of the watch tower". I saw this word combination "stand guard" in the dictionary, but it somehow sounds strange to me. Is it ok?
Why does it sound strange? It's a standard phrase. "To stand guard" means to be on duty, guarding something, normally standing up.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.