European Commission President Jean-Claude Juncker attends a press conference with European Council President Donald Tusk (not in the picture) at the EU headquarters in Brussels, Belgium, on April 29, 2017. The 27 European Union (EU) countries' leaders during their first official meeting since last month's British triggering of the Article 50 adopted unanimously the guidelines on Brexit negotiations with Britain, European Council President Donald Tusk said Saturday. (Xinhua/Gong Bing)