21.In the late 15th century, Christopher Columbus，a(n)___________navigator, led his men to sail across the vast ocean and reached some small islands in the now West Indies.
A. French B. Spanish
C. Italian D. English
22.American troops defeated the British at___________ in Northern New York. This was a great turning point of the American War of Independence，leading directly to an alliance between the U.S. and France.
A. Saratoga B. Trenton
C. Lexington D. Yorktown
23.In 1787，delegates from the states held a meeting in Philadelphia to make the Articles of Confederation adequate. The meeting came to be called the ___________ .
A. First Continental Congress B. Second Continental Congress
C. Constitutional Convention D. Independent Convention
24.Which of the following is NOT among President Theodore Roosevelt’s contributions?
A. The implementation of the Sherman Anti-trust Act.
B. The initiation of large-scale irrigation projects.
C. The adoption of the Hepburn Act of 1906.
D. The passage of the Federal Reserve Act.
25.___________Was the beginning of a long economic depression in the U.S. in 1929.
A. Business bankruptcy B. Serious unemployment
C. The stock market crash D. Foreclosures
