If you entered long queries in a Google search box, you would notice that it's difficult to edit them because Google optimized the size of the box for short queries. Things have changed and now you can much bigger queries and Google will adjust the search box's size after you perform a search.
Google limits queries to 32 words, but most people don't need that many words. The average number of words in a Google query was 4 at the end of 2007.
Here's a comparison between Live Search, Yahoo Search and Google Search for the query [how do you distinguish between a 64 bit and a 32 bit operating system], one of the most popular queries that start with "how do you".
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