midlatitude deserts worldwide, including those of the Great Basin. The broken valleys of the Great Basin
provided ready receptacles for this moisture.
- What is the geographical relationship between the Basin and Range Province and the Great Basin?
A. The Great Basin is west of the Basin and Range Province.
B. The Great Basin is larger than the Basin and Range Province.
C. The Great Basin is in the northern part of the Basin and Range Province.
D. The Great Basin is mountainous; the Basin and Range Province is flat desert. - According to the passage, what does the great Basin lack?
A. Snow B. Dry air C. Winds from the west D. Access to the ocean - The word 'prevailing' in line 4 is closest in meaning to
A. most frequent B. occasional C. gentle D. most dangerous - It can be inferred that the climate in the Great Basin is dry because ..............
A. the weather patterns are so turbulent B. the altitude prevents precipitation
C. the winds are not strong enough to carry moisture D. precipitation falls in the nearby mountains - The word 'it' in line 5 refers to ............
A. Pacific Ocean B. air C. west D. the Great Basin - Why does the author mention cottonwoods and willows in line 11?
A. To demonstrate that certain trees require a lot of water
B. To give examples of trees that are able to survive in a difficult environment
C. To show the beauty of the landscape of the Great Basin
D. To assert that there are more living organisms in the Great Basin than there used to be - Why does the author mention Owens Valley, Panamint Valley, and Death Valley in the second
paragraph?
A. To explain their geographical formation
B. To give examples of depressions that once contained water
C. To compare the characteristics of the valleys with the characteristics of the lakes
D. To explain what the Great Basin is like today - The words 'the former' in line 15 refer to ...............
A. Lake Bonneville B. Lake Lahontan C. The Great Salt Lake D. Pyramid Lake - The word 'accumulated' in line 17 is closest in meaning to ............
A. dried B. flooded C. collected D. evaporated - According to the passage, the Ice Ages often brought about .............
A. desert formation B. warmer climates C. broken valleys D. wetter weather
PASSAGE 10
The word laser was coined as an acronym for Light Amplification by the Stimulated Emission of
Radiation. Ordinary light, from the Sun or a light bulb, is emitted spontaneously, when atoms or molecules
get rid of excess energy by themselves, without any outside intervention. Stimulated emission is different
because it occurs when an atom or molecule holding onto excess energy has been stimulated to emit it as
light.
Albert Einstein was the first to suggest the existence of stimulated emission in a paper published in
1917. However, for many years physicists thought that atoms and molecules always were much more likely
to emit light spontaneously and that stimulated emission thus always would be much weaker. It was not
until after the Second World War that physicists began trying to make stimulated emission dominate. They
sought ways by which one atom or molecule could stimulate many other to emit light, amplifying it to
much higher powers.
The first to succeed was Charles H. Townes, then at Colombia University in New York. Instead of
working with light, however, he worked with microwaves, which have a much longer wavelength, and built
a device he called a "maser" for Microwave Amplification by the Stimulated Emission of Radiation.
Although he thought of the key idea in 1951, the first maser was not completed until a couple of years later.
Before long, many other physicists were building masers and trying to discover how to produce stimulated
emission at even shorter wavelength.