问题
单项选择题
当杆件内的拉应力低于比例极限时，应力与应变是（）关系。
A.正比
B.反比
C.相等地
D.倒数
答案
参考答案：A
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当杆件内的拉应力低于比例极限时，应力与应变是（）关系。
A.正比
B.反比
C.相等地
D.倒数
参考答案：A
| Directions: Complete the following passage by using the words in the box. Each word can only be used once. Note that there is one word more than you need. | |
He became a 1______ voce in the yean before the Civil War. A few weeks ago, the National Park Service (NPS) 2______ Douglass's birth and Black History Month with the reopening of his home at Cedar Hill, a 3______ site in Washington. D.C. The two-story house, which c ontains many of Douglass's personal possessions, had undergone a three-year 4______. (Thanks to the NTS website, however, you don't have to live in the nation's capital to visit it. Take a tour online.) He was born Frederick Augustus Washington Bailey to a slave mother and a white father he never knew. Douglass grew up to become the first black 5______ to bold a government office-as US minister and consul general (总领事) to Haiti. As a youth, he never went to school. Educating slaves was illegal in the South, so be 6______ taught himself to read and write. At 21 years old, he escaped from his slave owner to Massachusetts and changed his last name to Douglass, to hide his identity. In the 1850s, Douglass was involved with the Underground Railroad, the system 7______ up by antislavery groups to bring runaway slaves to the North and Canada. His home in Rochester, N.Y. was near the Canadian border. It became an important station on the 8______, housing as many as 11 runaway slaves at a time. He died in 1895. In his lifetime, Douglass witnessed the end of slavery in 1865 and the adoption of the 15th Amendment to the US Constitution (美国宪法修正案), which 9______ African-Americans the right to vote. |