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 will the speaker probably discuss next?

Which is the most popular sport in the US?

Which sentence best expresses the main idea of the first paragraph?

What is the main idea of the passage?

The word “acquire” in the passage mostly means .............

In order to show that learning to write requires effort, the author gives the example of ............

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

What can be inferred about machines that are not calculators or computers?

What does the passage mainly discuss?

Which of the following is NOT mentioned in the passage as full-time university students?

In paragraph 2, the word “those” refers to ...............

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

Which of the following was a suggested treatment for migraines in the passage?

Which statement would the author probably agree with?

The passage mentions which of the following as a reason for the importance of Lake Vostok to scientists?

In paragraph 2, cities like London, Copenhagen, and Amsterdam are mentioned ............

How many Americans are involved in telecommuting?

What does the word magni stand for?

The word neighboring would BEST be replaced with ............

It can be inferred from the passage that _____________

The word "dampened" in the passage is closest in meaning to _____.