问题
选择题
---How long has the United Nations ________?
--- ______1945.
A．come into existence; In
B．been in existence; Since
C．been in existence; From
D．come into existence; For
答案
答案：B
这题考查动词的用法：因为和how long连用，要表示状态的动词be in existence，come into existence是短暂动词，不能和表示一段时间连用，第二空填since，可以和现在完成时连用。选B。