3. Writing for the National Immigration Forum,Gregory Rodriguez reports that today's immigration is neither at unprecedented level nor resistant to assimilation.

【分析】复合句。句子主干为Gregory Rodriguez reports that..., that引导宾语从句Writing for…作谓语动词 reports的伴随状语。宾语从句中使用了 neither…nor 结构。
【译文】格瑞·罗徳里格兹在给“国家移民论坛”写的报告中提到，如今的移民既没有达到一个空前的水平，也没有表现出对这种同化的抵制。

4. The 1990 Census revealed that "a majority of immigrants from each of the fifteen most common countries of origin spoke English 'well' or 'very well' after ten years of residence."

【分析】复合句。句子主干为The 1990 Census revealed that..., that引导宾语从句。宾语从句主语为a majority of immigrants; from each of the fifteen most common countries of origin 是其后置定语;spoke 是谓语;English 是宾语；'well' or 'very well' 是状语;after ten years of residence为时间状语。
【译文】1990年的人口普査显示来自十五个主要移出国的大多数移民经过十年定居以后能‘较好’或‘很好’地使用英语。