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Read the following article and select the best answer. Article: Studies show farmland in Africa is often lacking in important nutrients. But researchers say combining different farming methods may help. Since the world food crisis several years ago, researchers have directed more of their attention to small farms. Most farms in areas south of the Sahara Desert are only about one or two hectares. One of the goals is to increase production without necessarily clearing more land to grow additional crops. American researchers say that can happen with greater use of an agricultural system called perennation. It mixes food crops with trees and perennial plants - those that return year after year. Mr. Reganold, who is with Washington State University, says poor soil may have resulted from years of weathering that washed away many nutrients. He says some farmers may have done more harm than good. He estimates that up to two billion dollars worth of nitrogen, phosphorous and potassium is lost from African soil each year. The scientist says the word perennation defines three systems that are already used in Africa. The oldest of the three is called evergreen agriculture. This is where farmers plant trees with their crops. John Reganold says farmers in Africa have been doing this for sixty years, but it seems to be growing in popularity. The method is gaining widespread use in countries such as Niger, Burkina Faso, Malawi and Zambia. The trees are planted among maize, millet or sorghum crops. They not only add nitrogen to the soil through their roots, but also through their leaves when they fall off and break down. At other times of the year, the trees can protect plants from strong sunlight. Mr. Reganold was one of three researchers who wrote a report about perennation. It was published in the journal Nature. Question: The word"perennation"mentioned in this passage _ . - is a farming method of planting food crops with trees - is a new farming method - can help African people produce more food than they need - is gaining widespread use around the world
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is a farming method of planting food crops with trees

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Read the following article and select the best answer. Article: Great white sharks! Just hearing that name _ . In reality, these big fish have more to fear from us than we do from them. For many years, people killed countless great white sharks in the waters around the United States. But thanks to conservation efforts, great whites are making a comeback in the U.S. Two recent studies show that the population of these sharks is rising along the east and west coast. Why is the growing population of a killer fish something to celebrate? "When you fish too many of them, you start to lose balance in the environment," says shark researcher Tobey Curtis. As the biggest killer, sharks help keep the populations of fish, seals, and other creatures they eat from growing too large. In spite of their importance, great white sharks had long been hunted for their meat and their fins . Then, in 1997, the U.S. government passed a law that didn't allow the hunting of great whites. Afterwards, the numbers of these sharks in the U.S. waters started to increase. The law wasn't the only thing that has helped great whites. Conservationists have also played a part in the sharks' comeback. The research group OCEARCH is using a method called tagging to help change people's attitudes about great white. They let the public follow each shark as it travels the world's oceans. OCEARCH also gives each tagged shark a name to help people form a closer connection with the big fish. The group's most well-known shark is named Katharine. She was tagged last year near Cape Cod, Massachusetts. Since then, thousands of people have tracked Katharine's movements on Twitter and the OCEARCH website. This helps people see sharks in a new way. Chris Fischer, the founder of OCEARCH believes learning to appreciate great whites will encourage people to do more to protect them. Question: The law passed in 1997 _ . - seemed very helpful - let scientists down - needed to be changed - made people like great whites
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seemed very helpful

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Read the following article and select the best answer. Article: (RAMALLAH, West Bank) -- Israel freed 26 Palestinian prisoners early Wednesday, the second of four groups to be released as part of an agreement that started the current Israeli-Palestinian peace talks, which had broken down since 2008. In all, 104 prisoners are to be released in four rounds over the coming months. In the West Bank and Gaza , the mood was overexcited as hundreds of Palestinians welcomed the prisoners back home, after many had spent more than 20 years behind bars. Crowds of people rushed toward the 5 prisoners released to Gaza, raising them on their shoulders, waving Palestinian flags and dancing to music. Relatives held signs that read "we will never forget our heroes." More than 2,000 people welcomed the 21 prisoners released to the West Bank, who were greeted at a ceremony by Palestinian President Mahmoud Abbas in Ramallah. Hazem Shubair, thrown into prison in 1994 for the death of an Israeli according to the Israeli Prison Service, was over delighted upon his return to Gaza. "I am speechless," he said. "Thanks to God. God is greater than the aggressors (meaning Israel)". Abbas said a final peace agreement with Israel was possible on the release of the prisoners. "There will be no final agreement without the release of all the prisoners," he told the violent crowd. Israel's Supreme Court earlier refused an appeal that intended to cancel the prisoner release. An organization of bereaved families behind the appeal has said it fears the prisoners, all in connection to the deaths of Israelis, will return to violence once freed. Question: There will be no final peace agreement between Israel and Palestinians until _ . - all the Palestinian prisoners kept in Israeli prisons are set free - all the prisoners return to violence once again - God is greater than the aggressors - Palestinians welcome some prisoners back home
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all the Palestinian prisoners kept in Israeli prisons are set free