问题 单项选择题

DNA的分子结构并不是一成不变的,在各种理化因素或环境因素的影响下,DNA上碱基排列顺序即遗传密码可能发生改变,从而引起基因突变。即使在正常情况下,DNA复制过程中也发。生频率极低的突变。  这段文字主要支持的一个观点是()。

A.DNA分子结构的可变性很强

B.DNA可能发生变异

C.DNA非常容易产生基因突变

D.DNA只有在特殊情况下才可能变异

答案

参考答案:B

解析:【解析】片段的首句就指出DNA的分子结构并非一成不变的,接下来则指出在各种理化因素或环境因素的影响下,甚至是在正常情况下;DNA也会发生突变。故选B。

阅读理解

The Official Theme for the 2005 World Exposition , Aichi,Japan is “Nature’s Wisdom”.

Name: The 2005 World Exposition, Aichi, Japan

Theme: “Nature’s Wisdom”

Site: Steo City, Nagakute Town, Toyata City, in Aichi Prefecture, Japan

Period: March 25 to September 25, 2005

Projected number of visitors: 15 million

Nature has provided humanity with a means to develop into complex societies based on this very basic relationship.

A vast network of knowledge and wisdom has evolved from this basic relationship between humans and nature. Nature's wisdom,her mysteries, inspiring beauty and power,have been unlocked by minds and scientific processes. Humans have become masters of this knowledge and have developed incredible technologies to employ energy and other resources.

In an increasingly overcrowded world, it is sometimes hard to focus beyond everyday life and onto the long term effects of our technological progress. Surely then,we must be reminded of the true wisdom found in a continuous relationship with nature. After all,we are in a world seeing an increasing amount of media coverage of international debates concerned about damage to the environment. It is commonly accepted that as far as the environment is concerned,it is a time to re-think our relationship with nature before it is too late.

Model Community

Continuous development is what the Eco-communities project at Expo 2005 is all about. The Eco-communities project has been expected to reuse energy and to reduce and make use of existing waste. As well, the entire Expo 2005 site--expected to host 25 million people over a six-month period--has been designed with the conservation(保持)of nature and the local environment as the top priority(优先考虑的事).

Finding answers for today' s world must be done in the background of technology. Thus,the idea of eco-communities was developed. Yet, an understanding of the socio-historical background is just as important in today’s richly multi-cultural world of economically various states and unions. And so the "Art of Life" Expo 2005 sub-theme was expected to be a model of human participation on a global scale. Expo 2005 offers to the people of the world an opportunity to come together and discuss many global issues that face humankind. It is a place to bring together the world's talent to create a model community for the future where humans can live in harmony with nature.

64.What is the period of Expo 2005 Japan?

A.May 1-October 31.            B.March 25-September 25.

C.May 1-October 30.          D.October 9-0ctober 21.

65. Which of the following themes is Expo 2005 Japan's?

A.Better City,Better Life

B.Interactions between Urban and Rural Areas

C.Nature’s Wisdom

D.Environment, Resource and Technique

66.According to paragraph 3, nature has many features except ______.

A. danger      B. power     C. beauty       D. wisdom

67. We can infer that______according the contents of the passage.

A.the relationship between nature and humans isn’t close

B.it is easier for us to find the true wisdom

C.it is important and necessary for human to protect environment

and nature

D.harmonious community and Art of life can’t realize

单项选择题