Question

【題目】【原創(chuàng)】The first theories and experiments with cloning began in the late 1880s as scientist sought to prove their theories about how the genetic material inside cells worked. Discoveries about the nature of DNA in the 1940s made it possible for cloning experiments to progress. In 1944 it was discovered that genetic information for each cell was kept in the cell’s DNA. When Oswald Avery found this genetic information, it gave scientists new ways to try to clone animals by using that genetic blueprint（生物細胞的模型）.

The first cloned animals were northern leopard frogs that were cloned by Thomas J. King and Robert Briggs in 1952. King and Briggs believed, based on their clones, that young cells were more practical for the cloning process. Cells that were taken from adults resulted in abnormally developed tadpoles(蝌蚪). The next successful cloning experiments also resulted in cloned frogs. John Gurdon cloned South African frogs in 1962. His use of adult cells disproved the previous theory that only young cells could be used in the cloning process with success.

While animal cloning had been the focus of cloning experiments, the 1960s also saw other types of cloning. In 1964, F. C. Steward took an adult root cell from a carrot plant and successfully cloned the plant. Throughout the rest of the 1960s, scientists continued to clone frogs and to discover more about DNA. The first gene was discovered in 1969.

In 1977, the first cloned mice embryos were created. The first mammal was cloned in 1984. The cloned sheep was quickly followed in 1985 with cloned cattle embryos. A cow clone was created in 1986 and several calves in 1993. That same year, human embryos were cloned for the first time. In 1995 and 1996, sheep were cloned, including the famous Dolly.

【1】The first paragraph serves as a(n) __________________________.

A. explanation B. conclusion

C. comment D. background

【2】When as the first plant successfully cloned?

A. In 1952 B. In 1960

C. In 1964 D. In1969

【3】How is the passage organized?

A. In order of frequency

B. In order of time

C. In order of importance

D. In order of preference

Answer 1

【答案】

【1】D

【2】C

【3】B

【解析】

試題分析：隨著科學(xué)技術(shù)的發(fā)展，克隆技術(shù)也成為了人們討論的熱點問題，那么克隆技術(shù)到底是怎么客服最初的困難而發(fā)展至今的呢？這篇文章將告訴你答案。

【1】D 寫作意圖題。文章從第二段開始就講述了科學(xué)家是如何克服難關(guān)，克隆出動物的過程，以及一些錯誤的理論如何通過實驗而得到糾正，故第一段主要介紹的是克隆技術(shù)面臨困難這一背景，選擇D。

【2】C 細節(jié)理解題。根據(jù)文章第三段的In 1964, F. C. Steward took an adult root cell from a carrot plant and successfully cloned the plant.可知，選擇C。

【3】B 文章結(jié)構(gòu)題。根據(jù)文章不斷出現(xiàn)的時間，可以推斷出文章是按照時間發(fā)展的順序來開展的，故選擇B。