彻底摧毁敌人的通讯设施。② Cities, such as Shanghai, Beijing and Guangzhou are major cities in China. 像上海、北京和广州等城市是中国的主要城市。③ Physics was his major subject in the university. 物理是他大学的主修课。④ He is a history major. 他是主修历史的学生。⑤ He majors in physics. 他主修物理。

5. A good example of how transportation is changing is the new maglev train，which is environmentally friendly, energy-saving and travels at an amazing speed of 430 km／h. 交通工具是如何变化的一个很好的例子就是新兴的磁悬浮火车，这种火车既友好于周围环境，又节能，并且以每小时430公里的惊人速度行驶。(p.43 Reading 'Transportation' 第4行)

　(1) 句中how transportation is changing (交通工具是如何变化的) 作介词of的宾语从句；which is...and travels...430 km／h是限制性定语从句，其先行词是train。amaze (vt.) 使惊奇，使吃惊；amazing (adj.) 令人惊异的；amazed (人) 惊异的，惊愕的。如：① Her knowledge amazes me. 她的学识令我吃惊。② Visitors were amazed at the achievements of the city during the past ten years. 参观者对这城市过去十年中的成就感到惊奇。③ I was amazed by the news of George's sudden death. 听到乔治突然去世的消息，我感到惊愕。④ What an amazing painting! 多么了不起的一幅油画啊!

(2) at a speed of ...以......的速度 The car is racing at a frightening speed of 200 m／h. 这辆小汽车以每小时200英里的吓人速度飞驰着。