建筑材料分为（）。 A.无机材料 B.有机材料 C.复合材料 D.高分子材料 E.合

根据对话内容，从下面方框中选择适当的单词或词组填空，使对话内容完整正确。

held，   be in use,   open,    but also,   improve

The Nanjing government is actively preparing for the coming Summer Youth Olympic Games, said the leader of the city. The event, which will be  小题1: from Aug 16 to 28, is not only a great chance for the city to carry out its development project,小题2: helps to develop the Olympic spirit and spread the importance of sports among Chinese youth, he added.
Nanjing won the bid in 2010 to host the 2014 games. Every four years, the event is  小题3:to players from 15 to 18 years old. “Hosting a huge event like this requires proper buildings, services and so on,” he said. “We want to use this chance to  小题4: ourselves.”
The city's transport system has been made better to meet the expected need from the event. Nanjing underground Line 10 will  小题5: in the near future. The total underground length will then have grown from 80 to 180 kilometers. At the same time, 1,400 new taxis and 2,530 buses will join the services as well.