True, because you have to have a topic in order to carry on a conversation. I'm not sure if that's the answer you were looking for but, i hope it helps.
It is true that an outline may consist of either phrases (topics) or sentences.
Outlines are those words or group of words that make up the proposed idea of the story or any academic paper to be written. they may be either in just phrases or they can also be in a form of a full sentence. There is no specific rule on how the outline of any paper should be written. Phrases or full sentences can all be employed as long as it can achieve its aim of referring to the proposed paper.
