TOEFL القراءة الأكاديمية — 25 سؤالاً

In regions where trees experience strong seasonal changes, many species form one visible growth ring each year. The width and density of these rings can preserve information about environmental conditions during the growing season. A wide ring may indicate favorable conditions, such as sufficient moisture and moderate temperatures, whereas a narrow ring can reflect drought, cold, competition, or other stresses. Scientists who reconstruct past climate from tree rings do not usually rely on a single tree. They compare overlapping ring patterns from many living and dead trees, a method known as cross-dating. Cross-dating helps researchers assign each ring to the correct calendar year and identify missing or false rings. Even then, ring width cannot be interpreted as a simple thermometer or rain gauge. Growth is influenced by multiple factors, and different species respond differently to temperature and precipitation. To strengthen climate reconstructions, researchers calibrate tree-ring measurements against modern weather records and often compare them with other evidence such as lake sediments, ice cores, and historical documents. When several independent records show similar patterns, confidence in the reconstruction increases.
What is the passage mainly about?

Cities are often warmer than surrounding rural areas, a pattern known as the urban heat island effect. Several features of the built environment contribute to this difference. Dark surfaces such as asphalt absorb a large portion of incoming solar energy during the day and release some of that stored heat after sunset. Buildings can also reduce air circulation, while vehicles and air-conditioning systems add waste heat to the environment. Vegetation tends to moderate temperatures because leaves provide shade and because plants release water vapor through transpiration. For this reason, urban planners increasingly use trees, parks, reflective roofs, and permeable surfaces as cooling strategies. These interventions do not affect every neighborhood equally. Their effectiveness depends on local climate, building density, available water, and maintenance. Researchers therefore caution against assuming that a single strategy will produce the same result everywhere. Instead, they recommend combining temperature measurements with neighborhood-level data before selecting interventions. The urban heat island effect is important not only because it influences comfort but also because high nighttime temperatures can increase health risks during heat waves by limiting the body’s opportunity to recover from daytime heat.
Select TWO cooling strategies mentioned in the passage.

Migration allows animals to exploit resources that vary across space and time. Birds may travel between breeding and wintering grounds, while some fish move between freshwater and marine environments. The benefits of migration can be substantial, but so are the costs. Long journeys require energy and may expose animals to predators, storms, unfamiliar habitats, and human-made obstacles. Migratory behavior is guided by a combination of inherited tendencies and environmental cues. Day length, temperature, food availability, and social information can all influence when movement begins. Navigation mechanisms differ among species. Some animals use the position of the Sun or stars, while others detect Earth’s magnetic field or recognize landmarks. Because migration depends on conditions at multiple locations, habitat loss at a single stopover site can affect populations that spend most of the year elsewhere. Conservation biologists therefore increasingly emphasize the protection of connected networks of habitats rather than isolated reserves. Climate change adds another complication by altering the timing of seasonal events. If insects emerge earlier in spring but migratory birds do not adjust their arrival time, the birds may miss a critical food peak.
Select TWO navigation methods mentioned in the passage.

In regions where trees experience strong seasonal changes, many species form one visible growth ring each year. The width and density of these rings can preserve information about environmental conditions during the growing season. A wide ring may indicate favorable conditions, such as sufficient moisture and moderate temperatures, whereas a narrow ring can reflect drought, cold, competition, or other stresses. Scientists who reconstruct past climate from tree rings do not usually rely on a single tree. They compare overlapping ring patterns from many living and dead trees, a method known as cross-dating. Cross-dating helps researchers assign each ring to the correct calendar year and identify missing or false rings. Even then, ring width cannot be interpreted as a simple thermometer or rain gauge. Growth is influenced by multiple factors, and different species respond differently to temperature and precipitation. To strengthen climate reconstructions, researchers calibrate tree-ring measurements against modern weather records and often compare them with other evidence such as lake sediments, ice cores, and historical documents. When several independent records show similar patterns, confidence in the reconstruction increases.
What is the purpose of cross-dating?

In regions where trees experience strong seasonal changes, many species form one visible growth ring each year. The width and density of these rings can preserve information about environmental conditions during the growing season. A wide ring may indicate favorable conditions, such as sufficient moisture and moderate temperatures, whereas a narrow ring can reflect drought, cold, competition, or other stresses. Scientists who reconstruct past climate from tree rings do not usually rely on a single tree. They compare overlapping ring patterns from many living and dead trees, a method known as cross-dating. Cross-dating helps researchers assign each ring to the correct calendar year and identify missing or false rings. Even then, ring width cannot be interpreted as a simple thermometer or rain gauge. Growth is influenced by multiple factors, and different species respond differently to temperature and precipitation. To strengthen climate reconstructions, researchers calibrate tree-ring measurements against modern weather records and often compare them with other evidence such as lake sediments, ice cores, and historical documents. When several independent records show similar patterns, confidence in the reconstruction increases.
Why can a narrow ring not automatically be interpreted as evidence of drought?