Recursos para estudiantes de inglés de todos los niveles, profesores y traductores. Para aprender o mejorar tu inglés en forma divertida.
Listening Comprehension - Comprensión Auditiva

Cómo realizar este ejercicio de comprensión auditiva

- Siempre encontrarás una pequeña introducción, que puede ayudarte a comprender el tema tratado.

- En los textos presentados se han ocultado algunas palabras, que deberás escribir en los casilleros correspondientes. A medida que lees el texto, escucha el audio con atención para descubrir dichas palabras.

- Quizás puedes deducir las palabras sin necesidad de escuchar el audio. Pero, pon atención al audio para confirmar si realmente se trata de la respuesta correcta.

- Puedes escuchar el audio cuantas veces sea necesario. Pero es recomendable hacerlo solamente dos veces (o tres veces como máximo) ya que esa es la forma en que normalmente se realizan estos ejercicios en exámenes y pruebas internacionales.

- Comprueba tus aciertos pulsando el botón "Corregir". Si no has podido completar todas las palabras, pulsa el botón "Solución" para ver cuáles eran las que te faltaban.

With Resistant Crops, Progress Can Raise New Problems
Topic: A new study shows how a gene that protects transgenic squash from viruses also makes the plants a more appealing target for insects. Transcript of radio broadcast. Source: VOA

Escucha el audio y completa los recuadros.

This is the VOA Special English Agriculture Report.

Plant breeders and genetic engineers keep working to give crops the strength to resist like insects, diseases, or floods.

But before you can resist a threat, you need to understand it.

We told you last week about a newly completed genetic map of the organism that causes late . That disease led to starvation in Ireland from potato shortages in the middle of the eighteen hundreds. The new genome could lead to better ways to protect potatoes, tomatoes and other crops.

Science may supply a crop. Yet that does not always guarantee demand.

Nik Grunwald from the United States Agriculture Department worked on the international team that completed the genome. He says it is possible to grow potatoes that resist late . But these may not look like Russet potatoes. And most American farmers grow Russets because, as Nik Grunwald puts it, "that is where the demand is."

Another example of scientific progress involves a bacterium known as Bt. Bt is used as a pesticide to fight cotton bollworms, corn borers and other pests. Scientists have found a way to grow cotton plants that contain a Bt gene, reducing the need for pesticides. But sometimes, when one problem gets solved, another one appears.

In China, some farmers and researchers blame a in pesticide use for an increase in pests unaffected by Bt. Also, there are concerns that some organisms could begin to resist the plants designed to resist them.

And scientists are reporting this week on what they call the "indirect costs" of a virus-resistance gene in Cucurbita. This is the species of squash that includes and gourds. The scientists say virus-resistant transgenic squash are grown throughout the United States and much of Mexico.

The genetically engineered squash are usually larger and than wild squash. But a three-year study showed that beetles like to feed more on the transgenic plants, increasing cases of wilt disease. The report by a team from the United States and China appears in the Proceedings of the National Academy of Sciences.

The researchers point out that gene flow between crops and their wild relatives is common and difficult to contain. They note concerns that wild plants could, as a result, genetically engineered resistances. And these could affect the natural balance in their environment.

And that's the VOA Special English Agriculture Report, written by Jerilyn Watson. I'm Bob Doughty.


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