What is a root? and please another my other question...thank you

Answer 1

A root word is one that can be expanded.
Examples: agree is a root word because we can add to it -- disagree, agreement, agreeably

The answer to your question about studying for English benchmarks is obvious as I read your last statement:

"i am having a A in english and i lived in California"

You need to work on verb tenses and capitalization. Your sentence should be:
I have an A in English and I live in California.

Answer 2

thank...do you have any suggestions on how to improve them?

Answer 3

Try this site for practice.

http://www.englishpage.com/verbpage/verbtenseintro.html