May : Happenings from the past
May 5,1884
Isaac Murphy , son of a slave and perhaps the greatest horse rider in American history , rides Buchanan to win his first Kentucky Derby . He becomes the first rider ever to win the race three times .
May 9 , 1754
Benjamin Franklin’s Pennsylvania Gazette produces perhaps the first American political cartoon （漫画）, showing a snake cut in pieces, with the words “ Join or Die” printed under the picture.
May 11,1934
The first great dust storm of the Great Plains Dust Bowl , the result of years of drought（干旱），blows topsoil all the way to New York City and Washington , D.C. .
May 19, 1994
Jacqueline Lee Bouvier Kennedy Onassis , former first lady and one of the most famous people of the 1960s , died of cancer in New York City at the age of 64 .
May 24, 1844
Samuel F.B. Morsr taps out the first message , “ What Hath God Wrought ,” over the experimental long-distance telegraph line which runs from Washington, D.C. , to Baltimeore , Md .
1. We know from the text that Buchanan is_____________.
A Isaac”s father B a winnning horse
C.a slave taking care if horses D.the first racing horse in Kentucky
2. What is the title of the first American political cartoon ?
A.Join or Die B.Pennsylvania Gazette
C.What Hath God Wrought D.Kentucky Derby
3. In which year did the former first lady Jacqueline die ?
A. 1934 B. 1960 C . 1964 D. 1994
4.Which of the following places has to do with the first telegram in history ?
A. Washington , D. C. B. New York City
C. Kentucky. D. Pennsylvania
，解得v3=0.5m/s;
，解得：Q=3.75J，EPm=3.75J.