【分析】复合句。主句主干为They have been spurred;which引导非限定性定语从句修饰DNA evidence。在定语从句中，Thomas Jefferson …Sally Hemings为省略引导词的宾语从句,作proved的宾语。主句中的过去分词结构 made available in 1998作DNA evidence 的后置定语。

　　【译文】1998年获得的DNA证据是驱使他们从亊该研究的部分原因，这一证据几乎很肯定地证明了托马斯·杰弗逊和他的奴隶莎莉·海明斯至少生了一个孩子。

　　【点拨】l)spur既可作名词也可作动词,本句中，该词为 动词.意为“激励，鞭策”。2)in part为表示程度的状 语.意为“部分地,在某种程度上”。3)father既可作动词,也可作名词,本句中是其动词用法,意为“作为父亲生育子女”。

　　【临摹】她的成功一部分是由于运气。

　　18.While Washington and Jefferson privately expressed distaste for slavery, they also understood that it was part of the political and economic bedrock of the country they helped to create.

　　【分析】多重复合句。while引导让步状语从句，主句主干为 they also understood that... ，此时的 that 引导宾语从句，宾语从句中又包含省略了关系词的定语从句they helped to create，修饰先行词 country。

　　【译文】尽管华盛顿和杰弗逊私下里都对奴隶制表示反感，但他们也认识到,奴隶制是他们一手缔造的国家的政治经济基础的一部分。

　　【点拨】distaste意为“厌恶,不喜欢”，可与taste一起联想记忆。19.The southern states would not have signed the Constitution without protections for the “peculiar institution, ”including a clause that counted a slave as three fifths of a man for purposes of congressional representation.

　　【分析】复合句。主句主干为The southern states would not have signed the Constitution；介词结构including a clause…对peculiar institution作进一步的解释，其中that引导的定语从句修饰clause。本句中用到了虚拟语气，would not have signed表达的是与过去亊实相反的假设，介词短语without protections for the "peculiar institution”表达了隐含的条件，相当于if they had not had protections for the "peculiar institution"。

　　【译文】如果不保护他们的“特殊制度”，南方各州是不会签署联邦宪法的。“特殊制度”中有一条规定：在选举国会代表时，一个奴隶可算作五分之三个公民。

　　【点拨】1)clause常见的意思为“分句，从句”，本句中意为“（法律、合同等的）条款，款项”。2)for purposes of“为了…...”。

　　【临摹】这幅画只是为了说明起见。

　　with或without表达隐含条件的用法

　　with或without在句中作状语，可以表示真实的条件，也可以表示虚拟的条件，理解为“如果...”或“若是没有…”。 例如：Without his help, I don’t know how to get started.没有他的帮助，我无从下手（真实的条件）。Without your help, we could not have completed the task ahead of time. = If it had not been for your help…若是没有你的帮助,我们不可能提前完成任务(非真实条件)。

　　20.The three-fifths formula handed Jefferson his narrow in the victory in the presidential election of 1800 by inflating the votes of the southern states in the Electoral College.

　　【分析】简单句。句子主干为The three-fifths formula handed Jefferson his narrow victory。介词短语in the presidential...作状语，其中包含by引导的方式状语。

　　【译文】3/5代表权的规定让选举团中支持杰弗逊的南方各州的人数增多，使杰弗逊在1800年的总统选举中以微弱优势胜出。

　　【点拨】l)hand sb. sth.本意为“递给某人某物”，本句中引申为“帮助某人获得某物”的意思。2)narrow victory意为“险胜，以微弱优势获胜”。3)inflate作及物动词时，原意为“使充气；使通货膨胀”，本句中意为“使大量增加”。

　　临摹答案

　　13. Americans are the tallest on average in the world.

　　14. A strong man will struggle with storms of fate.

　　15. sI cannot totally take your point, but by and large I think yours is reasonable.

　　17. Her success was in part due to luck.

　　19. This picture is for purposes of illustration only.