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.

The speaker’s main topic is ...................

The word “tolls” in paragraph 4 is closest in meaning to which of the following?

Which statement would the author probably agree with?

Sign language is said to be very picturesque and exact and can be used internationally EXCEPT for ..........

The word “it” in paragraph 2 refers to ................

The passage mainly discusses costume in terms of its _______

The word “this” in paragraph 3 refers to ...............

It can be inferred from the passage that, in summer, ________.

Which of the following statements does paragraph 1 support?

What does the phrase “you have got it out of your system” in passage mean?

According to the passage, ................ requires sensitivity and experience?

The word “rude” in paragraph 1 could be best replaced by .................

How many Americans are involved in telecommuting?

In the United States, Thanksgiving is ______.

According to the passage, what causes the unique color and look of hummingbirds?

A patient can still live a comfortable life even after the removal of ..........

It can be inferred from the passage that the sounds produced by the trees ...............

A paragraph following the passage would most probably discuss_________.

Which of the following best expresses the main idea of the second paragraph of the passage?

Doctors have tentatively concluded that cellphones may ________.

The “labellum” (line 7) is most comparable to .........