26. In paragraph 1 and 2, the text shows PTK's ____.文章第一二段，显示PTK的？

A, easy availability 容易获得性

B, flexibility in pricing 灵活的定价

C, successful promotion 成功推广

D, popularity with households  普及与家庭

   考察对原文第一二段的理解，以及对选项几个词组的辨析。由文章中出现的一些词汇，如All he needs to do，More than 60,000，without prescriptions(无须处方)，over-the-counter(通过柜台)，sell DNA tests directly to the public 可知PTK比较容易买到。所以A正确。

27: PTK is used to :

C, identify parent-child kinship

本题对应句子是Among the most popular: paternity and kinship testing. 随后又用实例解释了这个用途。Which adopted children can use to find their biological relatives and latest rage a many passionate genealogists and supports businesses that offer to search for a family’s geographic roots. 本题难度一般。其他选项干扰性不强。

28：Skeptical observers believe that ancestry testing fails to

A, trace distance ancestors 追踪远祖

B, rebuild reliable bloodlines 重建可靠的血统

C, fully use genetic information 充分利用遗传信息

D, achieve the claimed accuracy 达到所声称的准确性

    本题对应句子是倒数第二段的后半部分，Yet most ancestry testing only considers a single lineage,……for example just three generations back people also have six other great-grandparents or, four generations back, 14 other great-grandparents.理解即可知选项D正确。本题难度一般，主要靠理解，所要理解的内容也不难。其他选项干扰性不强。

29：In the last paragraph, a problem commercial genetic testing faces is

A, disorganized date collection 混乱的数据采集

本题也是考察对对应句子的理解，Databases used by some companies don’t rely on data collected systematically but rather lump together information from different research project. This means that a DNA database may differ depending on the company that processes the results. 命题和选项设置上没有太多的陷阱和干扰。只要理解句意即可。

30,An appropriate title for the text is most likely to be:

B, DNA testing and it’s problems

   本题是主旨题，做好前4个题目后对本题的解答很有帮助，同样，做好这个题后，可以反过来“串”下中心，验证前4个答案的准确性。最简单有效的方法是将每个选项带回原文比较，看是不是最符合全文的。