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UK Attention, Harry Potter fans: The sixth novel in J.K. Rowling’s Harry Potter stories, Harry Potter and the Half-Blood, will go on sale in the United States, Canada, Britain and Australia on July 16, 2005 Italy According to a recent study, there are now more dogs and cats in Italian homes than children. There are at least 14.5 million dogs cats in Italian homes compared with 8.7 million children under the age of 15．Italy has one of the lowest birth rates in Europe. A psychologist said that pets were loved by many young Italians who could not have or did not want to have children. In Ital空气成分中，体积分数约占78%的是 A．氮气            B．氧气             C．二氧化碳       D．稀有气体