某图书封面用了21600张对开纸，相当于（）。A.21600方  B.43.2令

Slavery Divides the Nation
Conflicting interests in north and south became increasingly apparent. Resenting the large profits obtained by northern businessmen from marketing the cotton crop, southerners attributed the backwardness of their section to northern expansion. Northerners, on the other hand, declared that slavery--the "peculiar institution" the south felt to be essential to its economy-- was wholly responsible for the region’s relative backwardness.

The chief anxiety northerners felt was that ______.
A. they could not make more profits from the cotton crops
B. some regions would be slave states
C. southerners were not responsible for the backwardness in the south
D. the southern states became a relatively compact political unit

As far back as 1830s, sectional lines had been steadily hardening on the slavery question. In the north, abolitionist feeling grew more and more powerful, encouraged by a free-soil movement vigorously opposed to the extension of slavery into the regions not yet organized as states. To southerners of 1850, slavery was a condition for which they were no more responsible than for their English speech or their representative institutions. In some coastal areas, slavery by 1850 was well over 200 years old, an integral part of the basic economy of the region. In 15 southern and border states, the black population was approximately half as large as the white, while in the north it was an insignificant fraction.
From the middle 1840s, the slavery issue became more important than all else in American politics. The south, from the Atlantic to the Mississippi River and beyond, was a relatively compact political unit agreeing on all fundamental policies affecting cotton culture, using only primitive implements, was singularly adapted to the employment of slaves. It provided work nine months of the year and permitted the use of women and children as well as men.

卵巢合成孕激素的部位为：

A．卵泡外膜细胞

B．卵巢间质细胞

C．卵巢门细胞

D．卵泡膜黄体细胞

E．颗粒细胞

-Help! There is a big snake near the house.

-_____ afraid. It will go away later.[ ]

A. Don't

B. Not

C. Be

D. Don't be

患者，女性，心脏联合瓣膜病10年，发热1个月，体温37.2～37.6℃，厌食，消瘦、贫血貌。确诊手段首选

A．胸部X线
B．血培养
C．心肌酶检查
D．测定血红蛋白
E．测定血沉

不属于骨折外因是（）

A.直接暴力

B.间接暴力

C.肌肉牵拉

D.累积性力

E.脓肿导致骨骼的病变