Today I’d like to begin a discussion on the problem of the heating up the earth. First, we’ll touch on the relationship between fluorocarbons and the ozone layer. You probably remember that the ozone layer is the protective shield around the earth. It is important to all life, because it filters out harmful ultraviolet light from the sun. Ozone itself, a form of oxygen, is regularly made by the action of the sun in the upper atmosphere. It is also regularly destroyed by natural chemical processes.

The problem now is that too much of the ozone layer is being destroyed. Scientists suspect that certain chemicals, such as fluorocarbons, are contributing to the depletion of the ozone layer. And how do we use fluorocarbons? The most common uses are in spray cans and cooling systems. The chemical pollution from these fluorocarbons can account for some of the ozone losses that have been reported. There are, however, new studies linking the sun itself to the depletion of the ozone layer. We’ll go into that new study more next time.

What does the word “filters out” in paragraph 1 probably mean?

Câu hỏi liên quan

• What is the main topic of the passage?

• It can be inferred from the passage that a soil sample with little or no clay in it ______.

•  According to the passage, the benefit of listening to music while learning and studying is that it ..............

ZUNIA12

• The word “accelerated” in paragraph 5 is closest in meaning to ______.

• According to the passage, Mantle could ______.

• Which sentence best expresses the main idea of the second paragraph?

• In compared with low-achieving students, successful students use ...........

• It can be inferred from the passage that the author believes that business operated by women are small because ................

• Beta blockers work on some physical and emotional symptoms because they ...........

• Why is the Mongolian women's status in the community “elevated”?

• Which of the following best summarizes this passage?

• According to the passage, which of the following is learning in broad view comprised of?

• When Business Week published “ The Portable Executive “, it implied that___________.

• The word “they” refers to___________.

• What is true of Lake Vostok?

• Why does the author mention "artistic, political, or pedagogic communication" in line 14-15?

• What is the topic of this passage?

• The word “it” refers to __________.

• This article is about ...............

• According to the passage, people respond to loud noises in the same way that they respond to ___.