allows to obtain only the first 1K snippets, in case we get more than 10K hits, we extend our queries by adding the most common term sequences appearing before or after the pattern.
if for the query "from * to Moscow" we got more than 10K hits and among the snippets we see '... bus from X to Moscow...' we create an extended pattern 'bus from * to Moscow' and use the term extraction in Section 3.2 to get additional terms.