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| 文章出处：学生大考试站 发布时间：2005-10-12 |
related primarily to
a. labor and education
b. transportation and insurance
c. utilities and repairs
d. products and services
8. According to the passage, which of the following is NOT a factor in the complete
understanding of price?
a. Instructions that come with a product
b. The quantity of a product
c. The quality of a product
d. Warranties that cover a product
9. In the last sentence of the passage, the word "they' refers to
a. return privileges
b. all the factors
c. buyer and seller
d. money
10. The paragraph following the passage most likely discusses
a. unusual ways to advertise products
b. types of payment plans for service
c. theories about how products affect different levels of society
d. how certain elements of a price "package" influence its market value
Questions 11 to 15 are based on the following passage:
Sound moves from its source to the ear by wavelike fluctuations in air pressure,
something like the crests and troughs of ocean waves. One way to keep from
hearing sound is to use ear plugs. Another way is to cancel out the sound with
anti-sound.
Using a noisemaker controlled by a microprocessor, engineers have produced
sound waves that are half a wavelength out of phase with those of the noise to
be quieted-each crest is matched to a trough, and vice versa. Once the researchers
have recorded the offending sound, a microrocessor calculates the amplitude and
wavelength of sound that will cancel out the crests and troughs of the noise. It then
produces an electric current that is amplified and fed to a loudspeaker, which
produces anti-sound and wipes out the noise. If the anti-sound goes out of
synchronization, a microphone picks up the leftover sound and sends it back to
the microprocessor, which changes the phase of the anti-sound just enough to
cause complete silence.
The research team has concentrated on eliminating low-frequency noise from ship
engines, which causes fatigue that can impair the efficiency and a
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