The police have issued a detailed ____________ of the missing boy. 

 I want to learn more about the American political system, but I don't know where to get the ________ . 

(2014·福建省普通高中质量检查)Because of H7N9 bird flu，all the chicken markets in Shanghai  have been closed and won’t open until further________.

Finding information in today’s world is easy, but the ______ you are likely to face is how you can tell whether the information you get is useful or not. 

The financial crisis has put the world economy in a difficult _________.