You used 638 character explanation in your araexpo.org web site's meta descriptions. We hope These length texts are not full of with keywords.Because search engines use the explanation of your web site in meta description part to give information in listing . Meta description part is not completely with keywords. Keywords are only used reasonably within sentence. Also you are using a very long meta description. Search engines read almost to 150 characters. If you write more than from this number, It will badly affect your web site's optimization quality. Our offer your meta description part should be the part which give advance information about your web site's content and It should not get over 150 characters.