TOEFL iBT Reading Practice Test 1
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The Rise of the Water Clock
ALong before mechanical gears and swinging pendulums measured the passage of time, ancient societies relied on the steady movement of water. The water clock, known to the Greeks as the clepsydra, or water thief, was among the earliest devices capable of tracking hours independently of the sun. Its principle was simple. Water dripped at a controlled rate from one vessel into another, and the changing level of the liquid indicated how much time had elapsed. Because it did not depend on daylight, the water clock could function at night, indoors, or under a clouded sky, a clear advantage over the sundial that preceded it.
BThe earliest surviving examples come from Egypt, where a stone vessel dating to roughly 1400 BCE was discovered in a temple. This container narrowed toward its base and bore markings on its inner wall. As water escaped through a small hole near the bottom, the falling level crossed these markings, allowing priests to schedule nighttime rituals with reasonable accuracy. Similar instruments appeared independently in Babylon, India, and China, suggesting that the underlying idea occurred to many cultures facing the same practical need.
CA persistent difficulty troubled early designs. As a vessel emptied, the pressure of the remaining water decreased, so the flow slowed and the clock ran unevenly. Engineers in the Greek city of Alexandria addressed this problem with remarkable ingenuity. During the third century BCE, an inventor named Ctesibius devised a system in which a constant supply of water kept an inner reservoir perpetually full, forcing any excess to overflow. Because the reservoir never dropped, the outflow remained uniform, and the resulting measurement grew far more reliable than anything before it.
DThe refined water clock soon acquired functions beyond simply marking hours. Some versions raised a floating figure that pointed to a numbered scale, while others rang bells or moved small mechanical birds. In Athenian courts, officials used water clocks to limit the time allotted to each speaker, ensuring that legal arguments did not run too long. A speaker whose water ran out was obliged to stop, and the vessel could be plugged when a witness was called so that the interruption did not count against the speaker’s allowance.
EThe influence of the device extended across centuries and continents. In the medieval Islamic world, scholars built elaborate water clocks that combined astronomy, automation, and artistry. The most celebrated example, constructed by the engineer al-Jazari in the twelfth century, took the shape of an elephant carrying an intricate mechanism that marked the hours with moving figures and sounds. Only with the arrival of the mechanical clock in Europe during the fourteenth century did the water clock gradually fall out of use, ending a tradition of timekeeping that had lasted more than three thousand years.
1According to paragraph A, what advantage did the water clock have over the sundial?
2The word clepsydra is described in paragraph A as meaning
3What does paragraph B suggest about the appearance of water clocks in different regions?
4According to paragraph C, why did early water clocks run unevenly?
5How did Ctesibius improve the accuracy of the water clock?
6It can be inferred from paragraph D that in Athenian courts the water clock was used to
7Al-Jazari’s most famous water clock was shaped like an elephant.
8The mechanical clock was more expensive to produce than the water clock.
9The oldest surviving water clock was found in a in Egypt.
10In Europe the water clock was replaced by the during the fourteenth century.
How Desert Plants Survive Drought
ADeserts rank among the harshest environments on Earth, where rainfall is scarce, temperatures swing sharply between day and night, and the soil often holds little moisture for long stretches. Despite these conditions, a surprising variety of plants not only survive but flourish. Their success rests on a set of adaptations that reduce water loss, store moisture when it becomes available, and time growth to coincide with rare periods of rain. Biologists group these strategies into three broad categories, each representing a different solution to the same fundamental challenge of living where water is precious.
BThe first strategy belongs to the drought escapers. These plants, many of them small annuals, avoid the worst of the dry season entirely by completing their whole life cycle within a few weeks. Their seeds may lie dormant in the soil for years, protected by tough coats, until a heavy rain triggers rapid germination. Within days the plants sprout, flower, and produce a new generation of seeds before the moisture disappears. The desert briefly bursts into color, then the parent plants die, leaving their seeds to await the next storm.
CA second group, the drought resisters, takes the opposite approach by storing water in swollen tissues. Cacti are the most familiar example. Their thick stems act as reservoirs, expanding after rain and contracting slowly during dry months. To protect this precious store, the plant has abandoned broad leaves, which would lose water quickly, in favor of spines that shade the surface and deter thirsty animals. A waxy outer skin further seals in moisture, and shallow but wide root systems allow the plant to absorb even the lightest rainfall before it evaporates from the surface soil.
DPerhaps the most elegant adaptation involves the timing of a plant’s breathing. Ordinary plants open the tiny pores on their leaves, called stomata, during the day to take in carbon dioxide for photosynthesis. In the desert heat, however, opening these pores under the sun would release enormous quantities of water. Many succulents solve this problem through a process known as crassulacean acid metabolism, or CAM. These plants keep their stomata closed during the day and open them only at night, when the air is cooler and less water escapes. The carbon dioxide absorbed after dark is stored as an acid and then used for photosynthesis the following day.
EThe third strategy relies not on avoidance or storage but on reaching distant water. Certain desert shrubs and trees, such as the mesquite, send roots astonishing distances downward in search of underground supplies. Records exist of mesquite roots extending more than fifty meters below the surface, far deeper than the plant is tall. By tapping into groundwater that shallower plants can never reach, these species remain green through droughts that would kill their neighbors. Together, these varied methods reveal how life, given enough time, can adjust to even the most unforgiving conditions, turning apparent wastelands into places of quiet abundance.
11According to paragraph A, the survival of desert plants depends on adaptations that do all of the following EXCEPT
12What is the main feature of the drought escapers described in paragraph B?
13According to paragraph C, why have cacti replaced broad leaves with spines?
14The word reservoirs in paragraph C is closest in meaning to
15According to paragraph D, why do CAM plants open their stomata at night?
16It can be inferred from paragraph E that the mesquite survives droughts mainly because it
17The seeds of drought escapers can remain dormant for years before germinating.
18Cacti are found more often in deserts than any other type of plant.
19CAM plants carry out photosynthesis at night rather than during the day.
20Mesquite roots have been recorded reaching more than fifty below the surface.
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