No one has yet succeeded in explaining the ___ of how life began.

Finding information in today’s world is easy．The_______is how you can tell if the information you get is useful or not。

As we all know, the present world financial crisis still has a bad       on the development of the economy of every country.

Were you given a _____, or did you have to do it?

With the _______ of the new album “Second Round”, May Day is now touring in major cities on the Chinese mainland, including Beijing, Shanghai and Chengdu.