we have submitted our article to a journal but for a long time status is under review . what can we mention in our eamil to editor for condition the article?
Just write saying that your article has been under review for a long time and ask for a status update. Don't overthink it. Editors see this kind of email all the time, enough so that they probably don't pay attention to the exact wording.
Only thing is be sure to include the information necessary to identify the paper - e.g. the article ID number.