On the surface? On the bottom?"

Yes. Surface and bottom of the sea.

"On the surface?" and "On the bottom?", are both incomplete sentences, and incorrect, but by now you have noticed that this is fairly common.

Thank you. I know.

Thank you. I know.

These types of sentences are not incorrect, Roger. That would leave us in the untenable position of speaking and writing incorrectly most of the time.

There is no rule of English that demands full and complete sentences. There are aspects of English where we tend to avoid them but that doesn't make them wrong for all aspects of English.

Okay, sentence fragments are okay. I wouldn't do it in an English class without clearly writing dialog, however.

I know. Languages always have some kind of omissions. But it's important for roger to give the complete sentense. Thank you.