相知有素

Explanation: Prime has always been. That mutual understanding has always been a good friend. 　　Source: Caidong Fan, Xu hut Father "Romance of the Republic of the popular" do not have the fourth of six back to the others, is the segment such as Chi Quan, President entourage for many years, know each other well-established today are too suspicious. " 　　Examples: Others do not have on that segment and other Chi Quan, President entourage for many years, ~, today also a bit suspicious. (Caidong Fan, Xu hut Father "Romance of the Republic of the popular" fourth six back)