Richard J. Daley: hope it helps :)
Belgium's ports were close to the British coast and German control of Belgium would have been seen as a serious threat to Britain.
Both groups are called Slavs. In the years before World War I, Serbia wanted all Slavic peoples to form one empire, free from rule by the Turks or Austria-Hungary. The Serbs' wish to unite all the Slavs in one empire is an example of. imperialism.