阅读下面短文并回答问题，然后将答案写到答题卡相应的位置上（请注意问题后的词数要求）。In the United States, train transportation is un

阅读下面短文并回答问题，然后将答案写到答题卡相应的位置上（请注意问题后的词数要求）。
In the United States, train transportation is unpopular pared with cars and airplanes. Most people like traveling by car or by air. Officials of the United States Department of Transportation made a study in 2001. The study is about how many miles Americans traveled by different means of transportation.
They only studied trips longer than 50 miles. The study showed that fifty-six percent of all miles were traveled in personal vehicle. Forty-one percent were traveled in an airplane. Two percent were traveled in a bus. And less than one percent of miles were traveled in a train. Amtrak is the national provider of train transportation in the United States. In the past ten years, the number of its passengers has increased by eighteen percent. Although the number of passengers has increased, it is still very small now. In countries such as France, Germany, or Japan, more people use trains. There are several reasons why many people     .
Firstly, Americans love to drive their own cars. On highways, cars can travel as fast as trains. These highways connect all major cities in America．Secondly, many travelers like to be independent. When they use their own cars they can decide when to travel. Thirdly, many buses travel between major cities. Bus travel is less costly than train travel. In a huge country like the United States, cities are far away from each other. In some cases, travel from one city to another by train may take more than a day. Airplanes can carry passengers over long distances much faster.
People who do not want to spend long time traveling by train decide to fly. For these people saving time is the most important thing.
【小题1】What is the best title of the passage? (Please answer within 8 words)
    
【小题2】What does the underlined word “it” refer to? ( Please answer within 4 words)
    
【小题3】Fill in the blank with proper words. ( Please answer within 6 words)
    
【小题4】Complete the following statement according to paragraph 2.( Please answer within 6 words)
When they use their own cars they are
    
【小题5】Why American people have to travel a long time if they go from one city to another?
(Please answer within 10 words)
     Train transportation in the USA is less popular.