Knowledge need to be accessed and queried. This is accomplished with the help of Query Languages, like the SPARQL. With a Query Language simple queries can be formulated. SPARQL is pretty much like SQL, it uses the same keywords (SELECT, FROM, WHERE, etc.), but in the end processing is little bit different, because all these facts represent large graphs. Therefore, such Query Language is a Graph Access Language and is based on graphs and tries to extract sub-graphs that match all the conditions that have been stated in the query. Basically all these statements are based on graphs. When the query is processed it will return an answer with contains all the Semantic Entities that fulfil the query.
It need to be careful by formulating a question as everything that is implicit in the mind of a user need to be made explicit to get the right answer.