Wouldn't it be great if you could just look up at the sky and read the weather forecast right away?
Well, you CAN. The forecast is written in clouds. If you can read that writing, you can tell something about the atmosphere. With some practice, you can become a pretty good weather forecaster. Who knows, you might even do as well as meteorologists (气象学家).
Meteorologists use much more information than just the appearance of the clouds to make their forecast. They collect data from all over the world. Then they put it into powerful, high-speed computers.
This does give meteorologists an advantage, because they can track weather patterns as they move from west to east across the country.
But you have an advantage, too. You have your brains. You can look at the sky and get your data directly. A meteorologist uses a computer forecast that’s several hours old to make a local forecast.
What are you seeing when you look at a cloud? “A picture of what moisture (水气) is doing in the atmosphere,”says meteorologist Peter Leavit. There’s moisture throughout the atmosphere. Most of the time you don't see it, because it's in the form of an invisible gas called water vapor.
Sometimes, the temperature of the air gets cold enough to cause the water vapor to change to liquid water. That’s called condensation, and we see it happen all the time, for example, when humid air from the shower hits the cold glass of a mirror. When enough water vapor condenses, droplets form in the air. These droplets scatter light. A cloud is seen.
Watching clouds over a day or two tells you a lot more than a single cloud about the weather to come. Changes in clouds show changes in the atmosphere.
You should begin to notice patterns. Certain clouds, fol1owing each other in order, can signal an approaching storm. But don’t take our word for it; see for yourself.
53. According to the passage, ordinary people can tell the weather because __________.
| A. they can look up at the sky | B. they can read weather writings |
| C. information is stored in computers | D. clouds signal the weather to come |
54. Your advantage in weather forecast is that __________.
| A. you can keep weather patterns in mind. |
| B. you have more powerful computers at home |
| C. your brain works as well as a high-speed computer |
| D. meteorologists give their data to you as soon as they get them |
55. A cloud is formed when __________.
| A. there are droplets in the air | B. light is scattered |
| C. moisture exists in the form of invisible gas | D. water vapor changes to liquid water |
56. This passage mainly tells us about how__________.
| A. to become a weather forecaster | B. to collect data directly |
| C. to be an assistant to a meteorologist | D. to keep an eye on the weather |
British and American scientists are raising genetically modified(转基因的) pigs in the hope of providing organs for transplant(移植) to humans, the project leader wrote in a newspaper Sunday.
Scientists in London and California have begun conducting the genetic experiments to find a solution to record–long waiting lists for organ transplants, Robert Winston said in an opinion piece written for Britain's Sunday Times.
In Britain alone, around 8,000 patients are waiting for a transplant.
"People needing a new heart or liver are waiting for someone else to die – usually a violent death in a traffic accident," Winston wrote in the newspaper. He said his team was "trying to modify pigs so their organs might save the lives of humans."
The scientists are introducing human genes into the animals to reduce the chances of the organs being rejected by patients, as has been common in previous attempts to use animal tissues, said Winston, who heads the Institute of Reproductive and Developmental Biology at London's Hammersmith Hospital.
Working with Dr. Carol Redhead of the California Institute of Technology, Winston's team has injected human genes directly into male piglets(猪仔), adding them to the animal's sperm(精子).
He said that pigs involved in experiments had successfully produced transgenic sperm, but acknowledged that British and European laws had prevented the team from using the pigs to mate.
The Sunday Times newspaper reported that the experiments would be moved to the United States following difficulties with funding and regulations in Britain. It said the pigs would be bred in Missouri.
"Our U.S. friends will benefit from our technology and the income we might have produced for Britain will be lost," Winston wrote.
Some scientists have previously blamed the idea of using animal organs for human transplant, saying the technique risks spreading animal viruses to humans. Winston said his research project is attempting to breed virus-free pigs.
49. Scientists are introducing human genes into the animals to ____________.
| A. make the organs healthier | B. reduce the pain of animals |
| C. make the organs live longer | D. reduce the chances of rejection |
50. Some scientists have blamed the idea of using animal organs for human transplant because ____________.
| A. the technique is not perfect now |
| B. humans may be infected with animal viruses |
| C. it is against laws and regulations |
| D. it may cause a conflict between humans and animals |
51. According to Winston, it seems ___________ to Britain to move the experiments to the United States.
| A. a pity | B. a pride | C. a disaster | D. a good idea |
52. It can be inferred from the passage that ____________.
| A. animal organs are commonly used for human transplant now |
| B. lots of patients need animal organ transplants now |
| C. examples of the animal tissues being rejected have happened |
| D. it is not safe to use animal organs for human transplant |