1.用定语从句合并下列句子.
My uncle had three sons.
Two of them died during the last earthquake.
答案： My uncle had three sons, two of whom died during the last earthquake.
请问1,这里为什么要用限定性定语从句呢?
2,为什么关联词是two of whom 呢? 请老师详细解释,谢谢!
答：1. 这里用的是非限制性定语从句.因为主句My uncle had three sons. 我的叔父（过去、曾经）有三个儿子. 句子的意思完整.不需要一个限制性的定语.
2. 因为引导定语从句要用关系词（关系代词或关系副词）.关系代词主要是五个：who, whom, whose, which, that. them是人称代词（宾格）,不能引导定语从句.
除了这种方式外,也可以这样：., of whom two died during ...
从句中two是主语,of whom是它的定语,可以是常见的介词+whom 来引导,更可以用主语 +of whom/ of which 这样的形式来引导非限制性定语从句.
原来的两句话也可以用并列连词and将它并列起来,成为一个并列句：
My uncle had three sons and two of them died during the last earthquake.
我的叔父曾有三个儿子,其中有两个在上次的地震时候死了.
现在将第二句话用一个从句的形式来表达.主句是前一句（重要的信息）,后一句是补充信息.
如用并列句或分两句写,则两句的信息是同等重要.（在翻译成中文时,不太容易表现出来）.