The thing is, people get terribly worked up about sentences. Does a sentence have to have someone doing something in it?
It's not easy, this sentence thing, is it?
Some people take a different approach altogether and talk about a sentence conveying a complete thought.
Errrmmm...I'm not really sure about that...Anyway, what if a sentence is about both my need for clarity and my fear of making an idiot of myself?
Some other people call grandly on the grammatical rules of the ancient tongues.
But, hey, eu!
Some speak of Capital Letters and Full Stops.
But what if a Capt. walks into a sentence?
(In any case, quite apart from that, I don't often bother with punctuation when I'm talking - though some people do use a limited system of "hand signals".)
In the end I have to admit to confusion and ignorance - except for the fact that I've been using sentences very nearly all my life without any trouble at all, so I must have been doing something right.
I can only conclude that, like tying a tie, it's probably easiest if you don't think too much about it.
Thing To Use Today: a sentence that someone will say isn't a sentence. So there! will probably do.
The word sentence comes from the Latin sententia, a way of thinking, from sentīre, to feel.