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 “depletion” in paragraph 2 probably mean?

Câu hỏi liên quan

• Which of the following is not mentioned as the field where English is the main language?

• The author’s tone in the passage is best described as .........

• The word “they” in line 10 refers to ..........

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• In the last paragraph, what does the author imply is a major function of hypotheses?

• The phrase “those forms” in the passage refers to all of the following EXCEPT ..........

• What can be inferred about the defense mechanisms of the sea cucumber?

• The word "derived" in line 13 is closest in meaning to ..............

• The word “excluded” is closest meaning to .............

• The word “flawed” in line 14 is closest in meaning to .............

• The reason why telecommuting has not become popular is that the employees .............

• Which of the following best summarizes this passage?

• In paragraph 1, “streaming pupils"________.

• The word “it” in paragraph 1 refers to ____________.

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

• The author states that the reason that infants need to avoid certain foods related to allergies has to do with the infant's ___________ .

• What is the main point the writer is trying to make in the last paragraph?

•  According to the passage, what are two causes of declining business school enrollments?

• According to the text, all of the following sentences are true EXCEPT _____.

• The word “glitches” in the third paragraph can be replaced by________.

• The BEST title for this passage would be ......