题目

回答下列问题： （1） 同学们利用如图所示方法估测反应时间，首先，甲同学捏住直尺上端，使直尺保持竖直状态，直尺零刻度线位于乙同学的两指之间。当乙看见甲放开直尺时，立即用手指捏直尺，若捏住位置刻度读数为h，则乙同学的反应时间为（重力加速度为g）； （2） 基于上述原理，某同学用直尺制作测量反应时间的工具，若测量反应时间的范围为0~0.5s，则所用直尺的长度至少为cm（g取10m/s2）；若以相等时间间隔在该直尺上面标Elizabeth Freeman was born about 1742 to African American parents who were slaves.  At the age of six months she was acquired, along with her sister, by John Ashley, a wealthy Massachusetts slaveholder. She became known as "Mumbet" or "Mum Bett".For nearly 30 years Mumbet served the Ashley family. One day, Ashley's wife tried to strike Mumbet's sister with a spade. Mumbet protected her sister and took the blow instead. Furious, she left the house and refused to come back. When the Ashleys tried to make her return， Mumbet consulted a lawyer, Theodore Sedgewick. With his help, Mumbet sued (起诉)for her freedom.While serving the Ashleys, Mumbet had listened to many discussions of the new Massachusetts constitu?tion. If the constitution said that all people were free and equal, then she thought it should apply to her. Eventually, Mumbet won her freedom―the first slave in Massachusetts to do so under the new constitution.Strangely enough ， after the trial ， the Ashleys asked Mumbet to come back and work for them as a paid employee. She declined and instead went to work for Sedgewick. Mumbet died in 1829, but her legacy lived on in her many descendants (后裔).One of her great?grandchildren was W. E. B. Du Bois, one of the found?ers of the NAACP, and an important writer and spokes?person for African American civil rights.Mumbet's tombstone still stands in the Massachu?setts cemetery where she was buried. It reads, in part： "She was born a slave and remained a slave for nearly thirty years. She could neither read nor write, yet in her own sphere she had no superior or equal."1.    What do we know about Mumbet according to Para?graph 1?A.    She was born a slave.B.    She was a slaveholder.C.    She had a famous sister.D.    She was born into a rich family.2.    Why did Mumbet run away from the Ashleys?A.    She found an employer.B.    She wanted to be a lawyer.C.    She was hit and got angry.D.    She had to take care of her sister.3.    What did Mumbet learn from discussions about the new constitution?A.    She should always obey her owners' orders.B.    She should be as free and equal as whites.C.    How to be a good servant.D.    How to apply for a job.4.    What did Mumbet do after the trial?A.    She chose to work for a lawyer.B.    She found the NAACP.C.    She continued to serve the Ashleys.D.    She went to live with her grandchildren.