Farmyard robots can cut down chemical pollution.
? Many of them use chemicals to kill weeds（杂草）. The trouble is, these weedkillers also kill wildlife, pollute rivers and are bad for the fields. . This kind of robot can cut weedkiller use by 90%. The robot is really smart because it only kills weeds but not crops（庄稼）.
Several cameras are built into the robot. The cameras facing the ground take photos to help the robot "see" the plants it passes.
The robot compares each photo to a library of plant photos to decide on which plants are weeds.
Robot arms move into position to give a small dose（剂量）of weedkiller on the weeds.
The robot is energy-friendly. .
How the robot will develop
The scientists do not want to just stop at the achievement they have made. . The improved model of robots will exactly discover weeds and dig them out instead of weed killers.
Robots could be programmed to leave some harmless weeds in the fields to support wildlife living there.
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A. But scientists have created a farmyard robot B. It is powered by the energy from the sun C. Where the robot is used D. They're working on the new designs to improve the model E. How the robot works F. Why do farmers choose the robot to work in their fields G. How do farmers usually kill weeds in the fields |
Every year in the U. S. there are about 500 tornadoes, a natural disaster (灾害;灾难), from Texas through Oklahoma, Kansas, Nebraska, lowa and into South Dakota. .
The "tornado season" is usually in spring, but the people in Tormado Alley are always ready for them and they always listen to the news. When the warnings come, . They find somewhere safe to stay. At home, the best place is the basement — a room that is used to store things under the level of the ground. If there is no basement, a room without windows like the bathroom is also a safe place.
" so that we can get ready and won't feel afraid when there's a tornado," says Tiffany Taylor, a high school student from Texas. "There's no basement at my school, so we usually go to the hallways on the lowest floors. Of course, we never sit near the windows."
After the tornado, people first check to see if it is safe to go out and then they check the buildings and the area for damage (破坏). !
In China, we are not so often troubled by tornadoes, but we do have disasters like earthquakes, or an unexpected fire. It is important to know how to keep us safe when a disaster happens. Remember: in order to stay safe in natural disasters, . For example, we'd better keep disaster plans in mind and practice often.
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A. That's why this area is called "Tornado Alley" B. people run out of their homes with fear C. At school, we often have practice D. we should get well prepared E. people follow their disaster plans F. And usually there is a lot of damage G. This is because there are a lot of tornadoes |
Do you know the reason why we feel tired in the middle of a class? Maybe you would say it is because the teacher's class is boring. Perhaps this is something you have not paid enough attention to or not yet noticed.
Purpose of sleep
Sleep helps our body heal (修复), grow, and stay healthy. It also gives us energy, so we can be active all day. Doctors and health scientists say: When you close your eyes and need t rest, sleep is just the very best! This is more than advice.
Seep time
Enough sleep is important to us. How much sleep do we need? New-born babies sleep most of the time. They can sleep 20-22 hours a day. Children need 10-12 hours of sleep a day. Teenagers need 8- 10 hours of sleep a day because they need lots of energy to grow into their adult (成人的) bodies. Grown-ups usually need 6-8 hours of sleep to keep active. That is why old people sleep less than young people.
Interesting facts
Almost everyone has their dreams while they sleep, but not all of them can tell their dreams clearly when they wake up. More surprisingly, some may even get up in their dreams and walk around. This is called "sleepwalking". Are you a sleepwalker? Or, is there a sleepwalker around you?
It's not just people that love to snooze (打盹). In fact, many animals have unusual or surprising sleeping habits. Some animals, such as bears and hedgehogs, sleep all through winter. The swift is a very fast bird that can sleep while it flies! Cute koalas sleep around 18 hours a day. Giraffes don't need much sleep at all. They usually sleep standing up.
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A. Sleepy animals. B. Why do we need sleep? C. Some people talk in their dreams. D. However, the real reason is probably that we don't have enough sleep. E. The older you get, the less sleep you will need. F. Some people never dream while they sleep. G. Clever animals |
Why Live Near the River?
Imagine pioneers traveling west in the 1800s. In those days, it was hard to find running water and shops where to buy things. As time went by, most pioneers had to make their homes near a river so that they could get water easily.
How did rivers help people live in the past?
Back in the pioneer days, people grew their own food, caught their own fish, and collected their own water. People also used rivers as roads, traveling on boats. Traders shipped goods (货物) to people from other areas.
When building many factories right next to rivers for the water's power to make machines work, some people choose to live near a river for working. They use the river to ship large goods, and some of them work at these fctories where power factories provide electricity to homes and businesses.
Who wouldn't want to live near a river?
Some people are nervous about living near rivers because rivers can cause floods (洪水). Every
once in a while, floodwaters rise higher than a house, ruining (泡坏) many things in the house.
Such waste causes water to smell bad and pollutes the crops (庄稼) we eat. Water and crops in polluted areas can make people very sick.
How do people decide where to live?
Rivers can provide jobs and fun activities in a beautiful place. However, those living by rivers should be willing to accept possible problems as well.
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A. Why do people live near rivers now? B. Why did people want to live near a river? C. Some factories put their waste into rivers. D. Staying close to a river was easy to get water for living. E. Some factories stop waste water from running into rivers. F. People who carry goods onto ships live near the river, too. G. People should think over the possible risks before deciding where to live. |
