Câu hỏi:

 Australia is a country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. It is the world’s sixth-largest country by total area. Australia’s capital is Canberra, and its largest urban area is Sydney. For about 50000 years before the first British settlement in the late 18th century, Australia was inhabited by indigenous Australians, who spoke languages classifiable into roughly 250 groups. After the European discovery of the continent by Dutch explorers in 1606, Autralia’s eastern half was claimed by Great Britain in 1770 and initially settled through penal transportation to the colony of New Wouth Wales from 26 January 1788. The population grew steadily in subsequent decades, and by the 1850s most of the continent had been explored and an additional five self-governing crown colonies established. On 1 January 1901, the six colonies federated, forming the Commonwealth of Australia. Australia has since maintained a stable liberal democratic political system. The population of 24 milion is highly urbanized and heavily concentrated on the eastern seaboard. Australia has the world’s 13th-largest economy and ninth-highest per capita income (IMF). With the second-highest human development index globally, the country ranks highly in quality of life, health, education, economic freedom, and civil liberties and political right.

How many groups of languages were spoken by Australians before the 18th British settlement?