In Abstract nouns^x, Adverbs^x

Hello, this is my first post here, I like to know these wordskilometercentimeterAre those words noun if they are standing alone ? if it's, what kind of noun it's, proper noun or abstract noun or etc ?After that, I want to indentify the part of speech of the following setence by using the...

There is no rule. Words with these prefixes have come about through accidents of history. The most usual is "un-", but always consult a dictionary. The following does not really answer your question, but you may find it somewhat useful anyway, especially if you're willing to work to dig some...