Read the passage carefully to find the answers for Questions 1 to 5. Answer each question in a maximum of 10 words. Remember to write the answers on the Answer Sheet. 　　In the United States also there were great changes, though the causes here were due only in part to the war; they sprang mainly from technical progress, and the development of mass-production, in which the United States henceforth was to lead the world. The cheap automobile, pioneered by Henry Ford, is a good example. In 1915 the United States contained 2.5 million cars; in 1920, 9 million. Only the new mass-production techniques made it possible to build all these cars and only the growing practice of “easy-payments” made it possible to sell them. By 1925 three out of four cars, new and old, were sold in this way. About the same proportion was covered against the weather; ten years earlier, forty-nine cars out of fifty were open ones.　　The last fact is important. The car had not only become cheap; it had become a comfortable room on wheels not just a means of transport. First in the United States, then in Britain and other countries, the car began to revolutionize everyday life. People no longer had to live near their work or close to a railway station. So began, in earnest, the problem which is still with us. The town centers, once full of life and sociability, began to wither; evening found them dead and deserted, nothing but bright shop windows and locked doors. The car brought many far-reaching consequences and it was blamed, rightly or wrongly, for the decline in churchgoing and the increase in immorality. More recently, it meant the virtual end of horse drawn transport and a growing threat to the supremacy of the railroad.　　Questions:　　1．What is the main cause for the great changes in the U.S.?　　2．the United States, 20 million cars could be sold in 1925 because of ______?　　3．What does “the last fact” refer to in the second paragraph?　　4．What is the main idea of this passage?　　5．According to the writer, it is doubtful whether the car should be responsible for ______?