united前面是加a還是加an

前面加冠詞a，例如：

1、It is essential that we present a united front.至關重要的是我們要表現得團結一致。

2、The Channel Tunnel has enormous symbolic significance for a united Europe.英吉利海峽隧道對於建立一個統一的歐洲具有重大的象徵意義。

3、A United Nations aid convoy loaded with food and medicine finally got through to the besieged town.一支聯合國援助車隊載着食物和藥物終於抵達了被圍困的市鎮。