How to search specific words in the text file in asp.net

Hello,

I read word file in my Application in asp.net and  want to search some specific string in the word file . for example i want to search like as string "xxx yyy zzz" from "my name is xxx yyy zzz  and i am a developer". I am search the word doc line by line and hence when I am looking for the search of a multi word string, I dont get the correct results sometimes as the occurance of the string may be split across two lines. At the same time, it is not possible to load the complete document in memory and search. What is an efficient way to search for a matching sentence( sequence of multiple strings ) in a paragraph using Asp.Net c#.

 

thanks

Pramod