Searching for Phrases
To run a keyword search for an exact phrase, enclose the phrase in double quotes.
Only the exact terms within the quotes are searched, no matter which search mode is selected.

Mutual merger agreements have been signed.
The reason is the document does not contain the exact term agreement.
When searching for phrases, stop words are also searched, even is stop word filtering is active.

Assume that stop word filtering is active, and an
is a stop word.
The query "close an agreement" will match only documents containing the exact phrase close an agreement even though an is a stop word.
The query "an" with no other terms in the quotes will not return any documents. A single term enclosed in quotes is interpreted as a plain exact match search, and plain exact match searches ignore stop words.

You can use phrases to search for these operators.