2014年12月英语四级听力练习:VOA慢速英语9.9(1)

2014-09-12 16:55:21来源：恒星英语

　　为了帮助同学们提高英语四级听力，小编特意整理了2014年12月英语四级听力练习:VOA慢速英语，供各位考生参考，希望大家多多练习。英语四级听力难度相对来说比较简单，语速跟VOA慢速英语差不多。大家加油备考吧。

　　Scientists have discovered the genetic secrets of two unpopular members of two favorite food families. They hope the discoveries will produce tastier tomatoes and stronger rice.

　　The scientists discovered the complete set of genetic rules of African rice and wild tomatoes. They published their studies in two reports in the journal Nature Genetics.

　　There are good reasons African rice and wild tomatoes have not been popular. Asian rice is more productive and easier to process than African rice. The wild tomato is poisonous.

　　Rod Wing is a plant biologist at Arizona State University. He helped map the African rice genes. And there is some good news to report.

　　“There are some varieties that have been kinda well-adapted to grow in kind of mangrove areas, which are quite a bit more salty than you would experience for Asian rice.”

　　Mr. Wing says African rice can grow in salty and even poisonous soil. And it can grow around weeds and in extremely dry conditions. He says this strength is increasingly important as climate change makes crop production more difficult. He says that this is important because the Earth’s population is growing quickly.

　　“There’s gonna be two-to two-and-a-half-billion more people on the planet in less than 40 years, and that’s a pretty scary scenario.”

　　Scientists will be able to make better rice faster. They can now identify the genes that control what is good about African rice and combine those genes with Asian rice.

　　The wild tomato also has some good qualities. Scientists found that it can grow in salty as well as very dry conditions, like the African rice. Bjorn Usadel of Germany’s RWTH Aachen University is one of the scientists who published the genetic maps of the two plants. The map identifies the genes that may be responsible for these qualities.

　　“The tomatoes are green and potentially there’s something inside that’s just not healthy; but there’s also other interesting things inside.”

　　The new map could also help improve the quality of tomatoes sold in food stores. Many people say these tomatoes do not taste very good. Mr. Usadel says researchers found differences in the genes of wild and farm-grown tomatoes that affect how they taste and smell.

　　“So, even though these wild tomatoes definitely don’t taste better, this population gives us actually an indication where the taste is coming from.”

　　The scientist says there is another use for the map. He says it will permit scientists to make sure that any new kinds of tomatoes developed from wild tomato do not carry any of its poisonous genes.

　　I’m Caty Weaver.

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