Earthquake Intensity & Observed Effects（强度与现象）
I.Felt by only a few people under very special conditions.
II. Felt by only a few people at rest, especially on the upper floors of buildings.
III. Felt noticeably indoors, especially on upper floors of buildings.
IV. Felt indoors by many people, outdoors by a few; some awaked.
V. Felt by nearly everyone; many awaked; dishes and windows break; plaster (灰泥) cracks (开裂).
VI. Felt by everyone; many frightened and run outdoors; heavy furniture such as tables and shelves moves.
VII. Everyone runs outdoors; small to moderate (中等的) damage(损毁) in usual buildings.
VIII. Considerable (相当大的) damage in usual buildings; monuments(碑) fall.
IX.Considerable damage in all buildings; ground cracks; underground pipes (管道) break.
X.Most buildings damaged; rails bend(弯曲); landslides (山崩) take place; water splashes(溅落) over banks.
XI.Few buildings left standing; bridges damaged; wide cracks in the ground; underground pipes break.
XII.Damage total; waves seen on ground; objects thrown into air.

     We often read the Air Quality Index （空气质量指标） or AQI reported in the newspaper. The AQI helps us understand what the air quality around us means to our health. The AQI uses colors, numbers and words to tell us about the air. Let's see what these colors and numbers mean.

    You know how much your telephone has changed over the past 10 years? Your car will change even more than that in the next 10 years. One of the biggest changes is that cars will drive themselves.

    "We certainly have the technology for it now." says Andrew Poliak of automotive(机动车辆的)technology supplier QNX." We expect self-driving cars to be a mainstream thing between 2020 and 2025."

    The American company Google has been working on self-driving cars for years. These cars are already on the roads in the United States and are truly self-driving. They have to steering wheels(方向盘）or pedals(踏板). Last week, the police ordered one of Google's cars to stop for driving too slowly on a public road. The car was not breaking any law, so no one was punished.

    Another American company, Tesla, added an "Autopilot" feature to its cars last month. With the Autopilot turned on, the vehicle drives itself. The car will speed up, slow down, brake and drive by itself. You can take over driving any time by turning the steering wheel or touching a pedal. The car uses sensors to know when driveway changing is safe and whether it should speed up or slow down.

    Tesla Autopilot is made for cross-country driving. It keeps you in the driveway and helps you avoid hitting other cars. It does not work well on local roads, for it will not stop at a red light or stop sign.

    Reporter Carolyn Nicander Mohr tried the Autopilot feature of a Tesla earlier this month. She had a hard time trusting the car to do what it should do. She thought about disabling the Autopilot feature many times during her trip. She wanted to take control at every bend in the road and hit the brake when the car in front of her slowed down. Yet the car drove perfectly.

    Other companies are working on self-driving cars, too. Marcedes-Benz, Audi, BMW. Volvo and Toyota all have plans for such vehicles.

    Can plants eat people? Probably not, but there are many plants that eat meat. Some of them are big. And they can eat small animals. One famous meat-eating plant is the Venus flytrap(蝇草).

    The Venus flytrap is a very strange plant. It grows in dry parts of the United States. Its leaves are like the pages of a book. They can open and close very quickly. Inside the leaves, there are three small hairs. If a fly (苍蝇) touches one of the hairs, the leaf closes quickly. The fly cannot get out. In about half an hour, the leaf presses the fly until it is dead. Then, the plant covers the fly. Slowly, the plant eats the fly.

    Why do plants do it? Most plants get what they need from the sun, the air, and the ground. In some places, the ground is very poor. It doesn't have all these important things, especially nitrogen(氮).Animal meat has a lot of nitrogen, so some plants eat meat to get what they need. Let's hope that some of the bigger plants don't get the same idea! 

    Americans were shocked to discover that the national bird was in danger of disappearing from the skies forever. Studies in 1970 showed only about 1,000, or fewer, bald eagles(秃鹰) in the country.

    The major cause of the problem was people. The spread of civilization(文明) destroyed many of the eagles' feeding and nesting areas. And the eagles were being affected by D-D-T and other insect poisons. The poisons were in the animals the eagles ate. They reduced the eagles' ability(能力) to use calcium(钙). This made the outside of the eagles' eggs very thin. Often, the eggs broke before baby birds were developed.

    In 1972, the U. S. government banned(禁止) D-D-T. People also became interested in protecting places where eagles live. And stronger efforts were made to carry out laws protecting the birds. Scientists began a program that placed baby bald eagles which were born under human care, into nests of wild bald eagles. Often, the wild birds accepted the babies.

    These efforts appear to have been successful in saving the American bald eagles. Today the number of the bald eagles has increased to more than 11, 000.