46) This movement，driven by powerful and diversemotivations, built a nation out of a wilderness and, by its nature, shaped thecharacter and destiny of an uncharted continent。
<解析> 本句and前后連接兩個(gè)并列的分句，主干部分為This movement built anation and shaped the character and destiny. “this” 指前文的“a tide of emigration”移民[微博]潮，“driven by.。�！狈衷~短語(yǔ)作后置定語(yǔ)修飾movement，同時(shí)起到主謂分隔的作用，”of a wilderness““of an uncharted continent“后置定語(yǔ)修語(yǔ)分別修飾a nation和the character and destiny 。
<參考譯文> 在各種強(qiáng)大動(dòng)機(jī)的推動(dòng)下，移民潮建立了一個(gè)國(guó)家并且根據(jù)其本質(zhì)塑造了一個(gè)未知大陸的性格和命運(yùn)。
47) The United States isthe product of two principal forces—the immigration of European people withtheir varied ideas, customs, and national characteristics and the impact of anew country which modified these traits。
<解析> 本句的主干是The United States is the product。
破折號(hào)后對(duì)是two principal forces的解釋說(shuō)明。本題的難點(diǎn)在于破折號(hào)后兩個(gè)and所并列的內(nèi)容。
<參考譯文> 美國(guó)是兩種主要力量之下的產(chǎn)物——即有著不同觀點(diǎn)，習(xí)俗和國(guó)家特色的歐洲移民和影響修訂這些特征的新國(guó)家。
48)But the force of geographicconditions peculiar to America, the interplay of the varied national groupsupon one another, an the sheer difficulty of maintaining old-world ways in araw, new continent caused significant changes。
<解析> 本句的主干是new continent caused changes。
<參考譯文> 但由于美國(guó)特有地理?xiàng)l件的推動(dòng)，不同民族之間的相互作用，以及維護(hù)原始老式方式的純粹困難，新大陸引起了重大變化。
49)The first shiploads ofimmigrants bound for the territory which is now the United States crossed theAtlantic more than a hundred years after the 15th- and -16-century explorationsof North American。
50)<解析> 本句的主干是The shiploads crossed theAtlantic. which 引導(dǎo)了定語(yǔ)從句修飾”territory“. ”more than a hundred years afterthe 15th- and -16-century explorations of North American“是狀語(yǔ)成分。
<譯文> 在15，16世紀(jì)探索過(guò)北美的一百多年之后，前往該領(lǐng)土(即當(dāng)今的美國(guó))的第一批移民橫渡了大西洋。
51)The virgin forest withits richness and variety of trees was a real treasure-house which extended fromMaine all the way down to Georgia。
<解析> 本句的主干是The virgin forest was atreasure-house. ”with its richness andvariety of trees”為后置定語(yǔ)修飾forest. which引導(dǎo)定從修飾treasure-house。
<譯文> 含有豐富多樣樹種的原始森林是一個(gè)真正的寶藏，它的覆蓋范圍從緬因州一直延伸到喬治亞州。
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