9.Among the most popular : paternity and kinship testing , which adopted children can use to find their biological relatives and families can use to track down kids put up for adoption.

【分析】复合句。句子的主干是Among the most popular : paternity and kinship testing...。因主句省略了谓语动词，此处冒号相当于be动词are。Which引导定语从句，先行词是paternity and kinship testing。定语从句本身又是由and连接的并列句，which在定语从句中作两个use的宾语，put up for adoption是过去分词短语作kids的定语。

【译文】在基因检测中，最受欢迎的是父子血缘关系测试——被收养的孩子可以利用这个测试找到自己生物学上的亲戚，家庭也可以用此来追查被受养孩子的下落。

【点拨】1）track down 意思是“跟踪找到，追查到”。2）put up for adoption指“将···送给别人收养”。

【临摹】多年来我一直在打听一些老朋友的下落。

10.This DNA can reveal genetic information about only one or two ancestors , even though , for example , just three generations back people also have six other great-grand-parents or , four generation back , 14 other great-great-grandparents .

【分析】复合句。句子的主干为This DNA can reveal genetic information... 。Even though引导让步状语从句，从句由or连接的两个并列分句构成。并列结构中的同等句子成分省略。

【译文】举例来说，只要上溯三代，一个人就会有八个曾祖父母，或者上溯四代，就会有十六个曾曾祖父母，即便如此，这种DNA只能揭示一到两位祖先的基因信息。

临摹答案

2.The sudden noise from the next room interrupted my trains of thought.

3.The more learned a man is , the more modest he usually is .

4.Many primary schools shut down early for the vacation for fear of the advent of earthquake.

6.He will break school rules if he goes on playing truant .

7.It is William who is not very cheerful and thus needs s holiday to pull himself together.

9.I’ve been trying to track down some old friends over the years .