[单选题]综采工作面两端头切顶线内巷道落山悬顶面积最大不得超过（ ）。
A.3m×5m
B.2m×5m
C.2m×10m
D.3m×5m
E.略
F.略
G.略
H.略

Text 2
People in the United States in the nineteenth century were haunted by the prospect that unprecedented change in the nation’s economy would bring social chaos. In the years following 1820, after several decades of relative stability, the economy entered a periodof sustained and extremely rapid growth that continued to the end of the nineteenth century. Accompanying that growth was a structural change that featured increasing economic diversification and a gradual shift in the nation’s labor force from agriculture to manufacturing and other nonagricultura pursuits
Although the birth rate continued to, decline from its high level of the eighteenth and early nineteenth centuries, the population roughly doubled every generation during the rest of the nineteenth century. As the population grew, its makeup also changed. Massive waves of immigration brought new ethnic groups into the country. Geographic and social mobility -- downward as well as
A. Women's lives significantly improved as the United States economy expanded
B. Women had more opportunities for employment in the western United States than in other regions
C. The home after 1820 was a superior social entity to that of the eighteenth century
D. Increased social fragmentation negatively affected middle class family life