What is {position held} of {F. W. de Klerk} that is {replaces} is {Alwyn Schlebusch} ?
What position did F.W. de Klerk replace Alwyn Schelbusch as?
SELECT ?obj WHERE { wd:Q151813 p:P39 ?s . ?s ps:P39 ?obj . ?s pq:P1365 wd:Q449929 }
select distinct ?obj  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q151813> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P39> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
?statement <http://www.wikidata.org/entity/P1365> <http://wikidata.dbpedia.org/resource/Q449929>
} 

Which job did F.W. de Klerk take over from Alwyn Schelbusch?