我开始学习SPARQL和rdflib。我在网上偶然发现了这个简单的例子：
import rdflib
# Now we create a graph, a representaiton of the ontology
g = rdflib.Graph()
# Now define the key words that we will use (the edge weights of the graph)
has_border_with = rdflib.URIRef('http://www.example.org/has_border_with')
located_in = rdflib.URIRef('http://www.example.org/located_in')
# define the things - base level objects that will be the nodes
# In this case first we have countries
germany = rdflib.URIRef('http://www.example.org/country1')
france = rdflib.URIRef('http://www.example.org/country2')
china = rdflib.URIRef('http://www.example.org/country3')
mongolia = rdflib.URIRef('http://www.example.org/country4')
# then we have continents
europa = rdflib.URIRef('http://www.example.org/part1')
asia = rdflib.URIRef('http://www.example.org/part2')
# Having defined the things and the edge weights, now assemble the graph
g.add((germany,has_border_with,france))
g.add((china,has_border_with,mongolia))
g.add((germany,located_in,europa))
g.add((france,located_in,europa))
g.add((china,located_in,asia))
g.add((mongolia,located_in,asia))
# now execute a sparql query to search as an example
q = "select ?country where { ?country <http://www.example.org/located_in> <http://www.example.org/part1> }"
x = g.query(q)
print type(x)
print list(x)
这很好，但我不想检索URI，我想要实际的国家名称：德国和法国。如何引用查询URI中的名称？