题目

现有以下物质： ①NaCl晶体 ②液态HCl ③CaCO3固体 ④熔融KCl ⑤蔗糖 ⑥铜 ⑦CO2⑧H2SO4⑨KOH固体 （1）以上物质中能导电的是________。 （2）以上物质中属于电解质的是_______，属于非电解质的是_______。 （3）以上物质中，溶于水且能导电的物质是________。 答案：④⑥    ①②③④⑧⑨    ⑤⑦    ①②④⑦⑧⑨    【详解】 在水溶液中或熔化状态下能够导电的化合物是电解质；在水溶液中和熔化状态下都不能导电的化合物是非电解质，物质的导电与溶液中自由移动的离子和金属的自由电子有关，电解质、非电解质必定属于化合物。所 （1）以上物质中能　　Digital television broadcasting, the “TV of the 21st Century”, was launched in Japan on Dec．1, 1999． 　　At first, the service is limited only in three of Japan's largest cities Tokyo, Osaka and Nagoya, but the Japanese government is aimed to make it available in all major Japanese cities by the end of 2006．The government says that by July 24, 2011, analog (模拟) television broadcasting in Japan will officially be a thing of the past． “As we mark 50 years since the start of analog television broadcasting in 1953, I believe we are at a historic moment as television evolves one step further,” said Japanese Prime Minister Junichiro Koizumi． 　　For now, it's estimated that about 12 million families around the area of the three above-mentioned cities can enjoy the service of digital television broadcasting．But because of Japan's mountainous terrain (地形), actual viewers may be as low as 300,000, according to scientists． 　　To watch digital television broadcasting, viewers need to get a digital TV set or attach a tuner (调谐器) to an ordinary one． 　　Scientists say the service of digital television broadcasting may not become popular in Japan for a while because most Japanese are not familiar with it now．A recent survey found 40 percent of Japanese TV viewers know nothing about the digital broadcasting technology． 1．What may limit the number of the viewers of digital television broadcasting? [　　] A．The TV viewers lack the digital television broadcasting technology． B．Most Japanese are living in mountains． C．The majority of Japanese are unwilling to fit a tuner to an ordinary TV set． D．Many people can't afford to buy digital TV sets． 2．The proper meaning of the underlined word evolves in the third paragraph is ________． [　　] A．falls behindB．overtakes C．overpassesD．develops 3．After reading the text we know that________． [　　] A．it's possible for Japanese to enjoy the service of digital television broadcasting in about seven years B．the Japanese government will make it available for all the Japanese to enjoy the service of digital television broadcasting in 2006 C．digital television broadcasting can't allow larger amounts of information to be passed D．it's difficult for the viewers to get familiar with digital television broadcasting 4．Which of the following is the best title of the passage? [　　] A．TV of the 21st Century Digital Television Broadcasting B．Digital Television Broadcasting Launched in Japan C．Advantages of Digital Television Broadcasting D．Digital Broadcasting Technology