La idea principal cubre todo el texto, no solo una frase.
En preguntas de detalle, la respuesta está escrita casi literalmente en el texto.
Estrategia paso a paso
Resume el texto en una frase antes de leer las opciones.
En textos literarios, fíjate en lo que hace y siente el personaje, no solo en lo que dice.
Trampas habituales
Opciones demasiado amplias (“todos”, “siempre”) o demasiado estrechas (un solo detalle).
Opciones que dicen lo contrario de un detalle del texto.
Ejemplo resuelto
Un texto cuenta que una ciudad plantó 10.000 árboles y que la temperatura de sus calles bajó 2 °C. Idea principal: plantar árboles puede refrescar las calles (no “los árboles resuelven el cambio climático”).
Preguntas de ejemplo
Intenta responder antes de abrir la solución. Las preguntas están en el idioma del examen.
Pregunta 1
Dificultad fácil≈ 1 min
Each year, a tree growing in a temperate climate adds a new layer of wood to its trunk, forming a ring. In years with plenty of rain, the ring tends to be wide; in dry years, it tends to be narrow. By measuring the rings of very old trees, scientists can learn about rainfall in periods before weather records were kept.
Which choice best states the main idea of the text?
AA. The rings in tree trunks can reveal information about rainfall in the past.
BB. Trees in temperate climates can add rings only in years with plenty of rain.
CC. Scientists have kept weather records for as long as the oldest trees have been alive.
DD. Trees form their widest rings during dry years.
Ver respuesta y explicación
Respuesta correcta: A. The rings in tree trunks can reveal information about rainfall in the past.
Explicación
The text explains that ring width reflects rainfall and concludes that measuring the rings of old trees tells scientists about rainfall before records existed. The correct choice states that idea.
Trees add a ring every year, including dry years (when the ring is narrow), so they do not grow only in rainy years. The text says the rings cover periods before records were kept, which contradicts the claim about records. Wide rings form in wet years, not dry ones.
Pregunta 2
Dificultad media≈ 1 min
In many desert plants, the pores that let in carbon dioxide for photosynthesis open only at night. Keeping these pores closed during the hot day greatly reduces the amount of water the plants lose to evaporation. The plants store the carbon dioxide they take in overnight and use it for photosynthesis once the sun rises. This strategy allows them to grow in places where water is scarce.
Which choice best states the main idea of the text?
AA. Some desert plants save water by taking in carbon dioxide at night and using it during the day.
BB. Desert plants carry out photosynthesis only at night, when cooler air limits water loss.
CC. Some plants lose more water at night than they do during the day.
DD. Desert plants store water in their pores to survive hot days.
Ver respuesta y explicación
Respuesta correcta: A. Some desert plants save water by taking in carbon dioxide at night and using it during the day.
Explicación
The text explains that these plants open their pores at night, store the carbon dioxide, and use it during the day, which cuts water loss. The first choice captures that whole idea.
Photosynthesis happens “once the sun rises,” not at night; only the intake of carbon dioxide happens at night (B). The text does not compare night and day water loss in other plants (C), and the pores let in carbon dioxide rather than storing water (D).
Pregunta 3
Dificultad difícil≈ 2 min
When a museum acquired a collection of nineteenth-century photographs of a coastal town, curators valued the images chiefly as examples of early photographic technique. Recently, however, researchers at the museum have begun using the photographs for a different purpose: by comparing them with the present-day shoreline, they have estimated how far the coast has eroded over the past 150 years. The same images, in other words, now serve as a scientific record as well as an artistic one.
Which choice best states the main idea of the text?
AA. The museum’s photographs have turned out to be more valuable as scientific records than as works of art.
BB. Nineteenth-century photographers intended their images to document the erosion of the coast.
CC. The coastal town has lost most of its land to erosion over the past 150 years.
DD. Photographs once prized for their technique now also serve as evidence of environmental change.
Ver respuesta y explicación
Respuesta correcta: D. Photographs once prized for their technique now also serve as evidence of environmental change.
Explicación
The text moves from the photographs’ original value (early photographic technique) to a new use (measuring coastal erosion) and sums up: the images are “a scientific record as well as an artistic one.” The last choice captures this.
“As well as” means the scientific use is added to the artistic value, not ranked above it (A). Nothing indicates what the photographers intended (B). The text says researchers estimated how far the coast has eroded, not that the town lost most of its land (C).