Is it true if you leave the US soil for a short period (less than 6 months), we have to wait for an addition of 2 years before we can get a US citi

There is no such rule. The general rule for residence in naturalization cases is that the individual must be a US resident for five years and have physically resided in the country for at least half of the time. Periods of time that you are outside of the country generally have no effect as long as they are short in duration. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.