My neighbor is very kind. I’ll never forget the ______ she’s done for me.

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

----What do you know the _____ of are the pig influenza in humans? ---- usually similar to regular human seasonal influenza .

       He told me that she had met one of my old friends in the street ________.

People are using more and more natural gas, wind and other forms of _____.