3) role of the U.S. in WWI
at the beginning of the war, Wilson said American policy was neutrality, But in fact it pursued a policy of pro-Ally(支持同盟国) partiality. American declared war on Germany on April 6, 1917.The Peace Conference,the Paris Conference,began on January 18,1919.The conference was actually a conference of division of colonies of Germany,Austro-Hungary and the Ottoman Empire and the grabbing of as much as possible from the defeated nations.The result of the Paris Conference was the emergence of the Versailles Treaty System in Europe.
4)characteristics of the 1920s
The 1920s in the U.S. has been described by many historians as a period of material success and spiritual frustration or confusion and purposelessness.the war changed the U.S. from a debtor nation into a creditor. There was further urbanization, new development of technology and mass production. The 1920s in the U.S. has been described as a period of material success and spiritual frustration. More people had cars. The government gave help to industry and business. There existed a highly aggressive and intolerant nationalism. There was the Red Scare in 1919 and 1920. There was the revival of the Ku Klux Klan(三K党反动组织复活)which claimed a membership of 5 million.
5)the Great Depression(1929-1937) and the New Deal 大萧条和新政
①no regulation or control over various kinds of investment companies.The banking system lacked stability. stock market speculation（股票市场投机）and over expansion of credit.(借贷过度膨胀)stock market crash (1929): America’s stock market crash came on October 24,1929, called the black Thursday 没有对各种投资公司调节与控制。银行系统缺乏稳定性。股票市场的投机与信贷过度膨胀。股票崩盘：1929.10.24，被称为黑色星期四。
②the gross national product(GNP) shrank(收缩) from $87 billion in 1929 to $41 billion in 1933. the unemployed went up; Misery and personal sufferings were widespread.国民生产总值从1929年的870亿降到1933年的410亿美元。失业率增加，不幸和痛苦到处可见。