阅读理解训练（18）AOn a sunny day last August, Tim heard some shouting. Looking out to the sea carefully, he saw a couple of kids in a rowboat were being pulled out to sea.Two 12-year-old boys, Christian and Jack, rowed out a boat to search for a football. Once theyd rowed beyond the calm waters, a beach umbrella tied to the boat caught the wind and pulled the boat into open water. The pair panicked and tried to row back to shore. But they were no match for it and the boat was out of control.Tim knew it would soon be swallowed by the waves.Everything went quiet in my head, Tim recalls (回忆). I was trying to figure out how to swim to the boys in a straight line.Tim took off his clothes and jumped into the water. Every 500 yards or so, he raised his head to judge his progress. At one point, I considered turning back, he says. I wondered if I was putting my life at risk. After 30 minutes of struggling, he was close enough to yell to the boys, Take down the umbrella!Christian made much effort to take down the umbrella. Then Tim was able to catch up and climb aboard the boat. He took over rowing, but the waves were almost too strong for him.Lets aim for the pier (码头), Jack said. Tim turned the boat toward it. Soon afterward, waves crashed over the boat, and it began to sink. Can you guys swim? he cried. A little bit, the boys said.Once they were in the water, Tim decided it would be safer and faster for him to pull the boys toward the pier. Christian and Jack were wearing life jackets and floated on their backs. Tim swam toward land as water washed over the boys faces.“Are we almost there? they asked again and again. Yes, Tim told them each time.After 30minutes, they reached the pier.1. Why did the two boys go to the sea?A. To go boat rowing. B. To swim in the open water.C. To get back their football.D. To test the umbrella as a sail.2. What does it in Paragraph 2 refer to? A. The beach. B. The wind.C. The boat. D. The water.3. Why did Tim raise his head regularly? A. To check his distance from the boys. B. To consider turning back or not. C. To take in enough fresh air. D. To ask the boys to take down the umbrella.4. How did the two boys finally reach the pier? A. They were carried to the pier by Tim on his back. B. They swam to the pier all by themselves. C. They were washed to the pier by the waves. D. They were dragged to the pier by Tim.参考答案1-4 CBAD BWhat will power your house in the future？Nuclear，wind，or solar power？According to scientists at the Massachusetts Institute of Technology (MIT) in the US，it might be leaves but artificial (人造的) ones.Natural leaves are able to change sunlight and water into energy. It is known as photosynthesis (光合作用)Now researchers have found a way to imitate this seemingly simple process.The artificial leaf developed by Daniel Nocera and his colleagues at MIT can be seen as a special silicon chip with catalysts (催化剂)Similar to natural leaves，it can split water into hydrogen and oxygen when put into a bucket of water. The hydrogen and oxygen gases are then stored in a fuel cell，which uses those two materials to produce electricity，located either on top of a house or beside the house.Though the leaf is only about the shape of a poker card，scientists claimed that it is promising to be an inexpensive source of electricity in developing countries. “One can imagine villages in India and Africa not long from now purchasing an affordable basic power system based on this technology,” said Nocera at a conference of the American Chemical Society.The artificial leaf is not a new idea. The first artificial leaf was invented in 1997 but was too expensive and unstable for practical use. The new leaf，by contrast，is made of cheap materials，easy to use and highly stable. In laboratory studies，Nocera showed that an artificial leaf prototype (原型) could operate continuously for at least 45 hours without a drop in activity.The wonderful improvements come from Noceras recent discovery of several powerful，new and inexpensive catalysts. These catalysts make the energy transformation inside the leaf more efficient with water and sunlight. Right now，the new leaf is about 10 times more efficient at carrying out photosynthesis than a natural one. Besides，the device can run in whatever water is available；that is，it doesnt need pure water. This is important for some countries that dont have access to pure water.With the goal to “make each home its own power station” and “give energy to the poor”，scientists believe that the new technology could be widely used in developing countries，especially in India and rural China.5Which of the following orders correctly shows how the artificial leaf is used to produce electricity?aartificial leaves split water into hydrogen and oxygenbthe hydrogen and oxygen gases are stored in a