Ants have a reputation for strength,organization and teamwork.But researchers have now discovered that a key secret to the success of ants is their ability to identify the importance of age in the work place. A study of Gentral American leaf-cutter ants has shown that the younger and stronger members are give the toughest job of cutting therough the leaves they harvest.Their sharp youn teeth do this job effectively,but as they get older their teeth become relatively worn and _ . But rather than being retired or abandoned by the group,the ageing ants are given a new role more suyted to their physical abilities.They become carriers and teansport the leaves back to the kingdom where they are harvested for food. The findings by researchers from the University of Oregon and the Oregong State University support previous research showin the survival of a leaf-cutter kingdom depends on the efficiency of is workers. "Cuting leaves is hard work,"said Dr.Robert Schofield,who led the research team."Much of the cutting is done with a V-shaped blade between teeth on their jaws.This blade starts out as sharp as the sharpest razor blade that humans have developed."But over rime the teeth become blunter and the cutting job slows down.The team estimated that,because of this age-related wear,a colony spent twice the energy cutting leaves than it would if all the ants had sharp blades.Its findings support the idea that wear and break can be significant problems for insects as well as largre animals. Like humans,leaf-cuttre ant recognize that older members of the group can still make a worhwhile contribution to society."This study shows an advantage of social living that we are familiar with,"said Dr.Schofield. The younger and stronger ants do the toughest job because _ . A) they can teansport the leaves effectively B) they have a sharp blade to cut leaves C) other members are busy with other work D) they can finish the job in a better organized way
B
(Question)
Tanzania Tarangire is a national Park which lies in Tanzania. The park itself covers an area of around 2,850 square kilometers, making it the sixth largest park of its kind in the country. I recently visited Tarangire to see what it was like.... One of the first sightings upon entering the park which I found was a huge herd of elephants. Our guide told us that Tagrangire was probably the best place in Tanzania to find large herds of elephants, and that their population in the park was around 2,500. We continued to watch the elephants as they stood under trees and scratched themselves against the trees to hit the spot of an itch . To the right of the elephant herd, we noticed a big tree! Our guide informed us that this was a Baobab tree and that they could live for hundreds of years. Compared with this tree, the elephant just looked like dwarfs ! We were informed that Tarangire was one of the best National Parks in Africa to see so many Baobab trees. As we continued our drive through the park, we finally reached a watering hole. Our guide warned us that there were lions all around us. It took us all a while to find them, but there they were! Most of them are resting in the shade under brushes, but there was one that was drinking from the watering hole directly in front of us. We then noticed just to our right, there were a couple of fresh zebra corpses -- it seemed as if the lions which were resting had killed them! We were unlucky not to have seen the actual kill, as our guide had mentioned that the zebra corpses were fresh and the kill had occurred within the last hour. Our final big sighting was one that none of us were expecting to see, even our guide! We pulled over to where there was a large gathering of cars, with a sleeping leopard there! We took photos happily and excitedly and observed its surprising body before returning to our hotel as it was getting late. So, I hope you enjoyed my description of Tarangire, and that I have inspired you to add this amazing park to your very own Tanzania travel route. What did they see when they stopped with some other cars? A) A large herd of elephants B) Some lions C) Some zebras D) A leopard
(Answer)
D
Ques: Here is a story told about an American general who was a very important figure in the American army during the First World War. Everybody in the United States knew him and many people wished to have a picture or something of his in their homes. Soon after the war the general returned to Washington. One day he went to a dentist and had six teeth pulled out. A week later the general heard that his teeth were being sold in curiosity shops as $ 5 each. On each of the teeth there was a label with the name of the general and words: "Buy these teeth and show them to your friends at home." The general got angry. He rushed to his office and ordered six officers to go around the city and buy all his teeth. The officers went out and visited every curiosity shop in the capital. They were away from the office all day. In the evening they returned and put on the table in front of the general the teeth they had bought. They had collected 175 teeth. In the evening, the officers went back with all the teeth which cost _ . A) $ 785 B) $ 1,050 C) $ 157 D) $ 875
Ans: D
Agricultural experts met in Ethiopia last week to discuss ways to help sub-Saharan Africa become a major producer of wheat. The area traditionally produced little wheat, while North Africa was the grain basket. Wheat production fell sharply in sub-Saharan countries during the 1980s. In the 1960s, attempts were made to grow wheat in sub-Saharan Africa, including South Africa and Zimbabwe. But those countries found it was less costly to import wheat from Europe and the United States. Another problem is that Africa's wheat farms were often far from population centers. There also were transportation issues. And some lowlands were not a good place to grow wheat. Hans Joachim Braun,one of the experts, says now is a good time to increase wheat production. In the last four years we have seen three major price hikes, where the wheat price and other staple process exploded. And that puts a big, big bill on countries which are depending on wheat imports, and Africa is the biggest wheat importer. He also says demand for wheat in sub-Saharan Africa is growing faster than for any other crop. With higher income people would like to have more diversified food. But that is possible not the most important one. The most important one is that there is a tremendous migration of in particular male labor to the cities. And wheat products are convenient food because you can easily buy it. It's easy to process and you also can store it for a few days, which is different from some of the maize and rice products. There are three possible challenges for growing more wheat in Africa: climate change, disease and pests, like insects. Mr. Braun says rising temperatures should not have a major effect on wheat. In fact, he says, it could help wheat grow in areas with high rainfall totals. As for fighting disease and pests, experts suggest growing more resistant crops. In addition, railroads and roads would have to be improved so large amounts of wheat could be moved to large markets. According to Mr. Braun the main challenges for growing more wheat in Africa are _ . A) climate change and disease B) resistant crops and climate change C) rising temperatures and disease and pests D) disease and pests and inconvenient transportation
D