Question: What nation of the Sahel through which the Niger River flows is the geographic location where Yoruba is a spoken dialect?
Answer(s):
answer: Nigeria

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.05csx)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.05csx ns:location.location.partially_containedby ?x .
?x ns:common.topic.notable_types ns:m.01mp .
?x ns:location.location.partially_contains ns:m.0l5_l .
?x ns:location.country.languages_spoken ns:m.01zycf . 
}