商务谈判目标的层次包括：（） A.最低限度目标 B.可以接受的目标 C.互利目标 D

如图所示，一束光线射到空气和某种玻璃的分界面后在两种物质中的传播路线，相互垂直的两根直线分别表示界面和法线，由图可知：入射光线是______，折射角为______度，界面的______侧是玻璃．

植株生长需要的营养有______、______和______，它们分别是通过植物的______和______获得的．

二尖瓣区收缩期器质性杂音可见于下列疾病中的（）

A.扩张型心肌病

B.贫血性心脏病

C.甲亢性心脏病

D.高血压性心脏病

E.二尖瓣脱垂综合征

少儿旅游者的心理特征包括（）

A.纪律感强

B.热衷购物

C.比较务实

D.习惯于接受指示

E.游兴易出现波动

The first mention of slavery in the statutes of the English colonies of North America does not occur until after 1660--some forty years after the importation of the first Black people. Lest we think that slavery existed in fact before it did in law, Oscar and Mary Simon assure us that the status of Black people down to the 1660’s was that of servants. (46) A critique of the Simons’ interpretation of why legal slavery did not appear until the 1660’s suggests that assumptions about the relation between slavery and racial prejudice should be reexamined, and that explanations for the different treatment of Black slaves in North and South America should be expanded.
(47) The Simons explain the appearance of legal slavery by contending that, during the 1660’s, the position of White servants was improving relative to that of Black servants. Thus, the Simons argue, Black and White servants, heretofore treated alike, each attained a different status. There are, however, important objections to this argument. First, the Simons cannot adequately demonstrate that the White servant’s position was improving during and after the 1660’s; several acts of the Maryland and Virginia legislatures indicate otherwise. Another flaw in the Simons’ interpretation is their assumption that prior to the establishment of legal slavery there was no discrimination against Black people. It is true that before the 1660’s Black people were rarely called slaves. But this should not overshadow evidence from the 1630’s on that points to racial discrimination without using the term slavery. Such discrimination sometimes stopped short of lifetime servitude or inherited status--the two attributes of true slavery--yet in other cases it included both. (48) The Simons’ argument excludes the real possibility that Black people in the English colonies were never treated as the equals of White people.
This possibility has important ramifications. (49) If from the outset Black people were discriminated against, then legal slavery should be viewed as a reflection and an extension of racial prejudice rather than, as many historians including the Simons have argued, the cause of prejudice. In addition, the existence of discrimination before the advent of legal slavery offers a further explanation for the harsher treatment of Black slaves in North than in South America. (50) Frey and Terry have rightly argued that the lack of certain traditions in North America--such as a Roman conception of slavery and a Roman Catholic emphasis on equality--explains why the treatment of Black slaves was more severe there than in the Spanish and Portuguese colonies of South America. But this cannot be the whole explanation since it is merely negative, based only on a lack of something.