单选题 Genes that control factors such as size, color and shape determine the differences in fruit. And now that scientists have discovered how to detect different genes, farmers can hand over a young and tender branch to have its genes checked prior to planting. It works the same way as a detective (侦探) checking finger-prints. Once farmers know which trees are good and which are bad, they can discard the bad ones. Farmers can even create new varieties according to their individual tastes.
In the past three years, tens of thousands of tests were carried out to determine the genetic (基因的) features of fruit. Zhang, a Chinese scientists, showed a photo of a DNA (脱氧核糖核酸)-test and pointed to the shining lines on it, saying that the lines were genetic signs that tell us what a tree's fruit will be like. For example, the ordinary pear tree bears fruit after four years. But now it only takes a month to test the DNA from a young leaf and a farmer will know everything about its fruit. By mixing different types of trees with suitable genes, farmers can create whatever fruit trees they want.

单选题 Detecting different genes in plants is like ______.
A. the examination of human finger-prints
B. the development of new varieties of fruit
C. the checking of young and tender branches
D. the distinction between bad trees and good ones
【正确答案】 A
【答案解析】[解析] 第一段第三句说：识别不同的基因与侦探检查指纹是一样的。所以答案是A。
单选题 The word "discard" (Para. 1, Line 5) most probably means to ______.
A. put aside B. give up C. deal with D. take up
【正确答案】 B
【答案解析】[解析] 第一段第四句说：一旦农夫们发现了哪棵树好，哪棵树不好，就会放弃坏的。第五句说：农夫们甚至会根据他们不同的口味创造新的品种。因此可以推断出，discard的意思是“抛弃”。A．put aside的意思是“搁置一旁，存起来”；B．give up的意思是“放弃”；C．deal with的意思是“处理”；D．take up的意思是“从事”。
单选题 We learn from the first paragraph that the study of genes ______.
A. has greatly affected the way of planting trees
B. has been a popular planting procedure
C. will change the taste of individuals
D. will play a vital role in fruit production
【正确答案】 D
【答案解析】[解析] 第一段第一句说：控制诸如大小、颜色和形状的基因决定了水果的不同。选项D的意思是研究基因在水果生产中将起重要的作用。所以选D。
单选题 Now farmers can tell whether a fruit tree is desirable or not by ______.
A. having a DNA-test of a young leaf of the tree
B. mixing different types of suitable genes
C. checking its young branches before planting
D. comparing the shining lines with the genetic signs
【正确答案】 A
【答案解析】[解析] 第二段第四句说：现在只要一个月就能检测出嫩叶的DNA，由此农夫就能知道有关果实的一切。所以选A。
单选题 The passage tells us that the new genetic technology will enable farmers to ______.
A. increase the DNA of a fruit tree
B. improve the quality of fruit
C. make use of the shining features of fruit
D. change the cycle of fruit production
【正确答案】 B
【答案解析】[解析] 从第二段可以知道，通过DNA检测，可以了解未来的果实是否受欢迎，农夫还可以对不同的果树进行杂交，创造出自己所需的果树。也就是说，了解基因可以改进果树。