In Numbers^x, Determiners^x, Commas^x

Hello, this is my first post here, I like to know these words kilometer centimeter Are 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...

You have problems with determiners, plurals, verb tenses, prepositions and general grammatical structure. I've corrected the first paragraph for you and highlighed problems in the second. In the second paragraph you have started inserting a space before commas, which is incorrect. The...