1. Against
Think of antagonist in a story. The antagonist goes against the main character. Someone who antagonizes you is going against you in order to make you angry on purpose.
2. Where they are located in the word.
A prefix is at the beginning of a word. The root is in the middle of the word (if there is a prefix). The suffix is at the end of a word.
3. profit
Pro can be used as a prefix, but it is not in the word profitable.
4. Thousands
When you add all the Greek and Latin prefixes, roots, and suffixes, there are thousands.
5. to help with all of the above
Understanding how words are made and where they come from help a reader to understand their meaning as well as help with pronunciation and spelling.
