①The growth in tall buildings worldwide, most of which have large glass panes, has led to a great need for window washers. Though the job, which earns workers as much as $35 an hour, can be lucrative, accidents are not uncommon. However, the dangerous chore may soon be done by Ozmo, an intelligent window cleaning robot, with humans controlling from the safety of the ground.

②Much like humans, Ozmo, hanging off the sides of the building, uses its arms and brushes to clean the dirt on the glass panes. A 3-D map of the building programmed into its system allows the robot to skillfully move up and down. Computer vision and touch sensors(传感器) enable it to move out of the way in case of unexpected events, such as the sudden opening of a window. And the robot will self-correct and move around it so as not to break a window.

③Unlike other window washers, the robot cleaner does not require soap or Windex to clean the glass. Instead, it uses purified water and a process called reverse osmosis(反渗透) to do the job. It is environmentally friendly.

④While it takes three cleaners 480 hours each to clean the windows of a 40-story glass building, the robot will single-handedly complete the task in just 80 hours. However, unlike other robots, Ozmo will not take the place of human workers, only making their jobs safer. Human workers will control the robot from below.

⑤Whether Ozmo, which is still being tested, does as good a job as humans remains to be seen. Past efforts to use a robot to do this dangerous job have not been successful, because the machines do not have the same eye as humans and often miss the soot(烟垢) collected on window corners.

Can you imagine a world without insects? Without ants or flies in your house, it might sound great. However, the results may be out of imagination.

The number of insects has dropped by half in the past few years, according to a British biologist Dave Coulson.

You may think small insects are not important. But in fact they are the main part of the species(物种) on Earth.

Insects are indeed on the way to die out, according to the first review of insect population. The researchers say the main reason for this is the use of pesticides(杀虫剂) because they destroy insects' living areas. Also, weather change is another important cause.

"Unless we change our ways of producing food, insects will go down the way to disappear in a few years," the researchers wrote in the review. "This will have huge influences on the planet's ecosystem(生态系统)."

We need insects to pollinate(授粉)crops. They also break down dead plants and animals, which can keep the soil healthy. Without insects, many animals would have nothing to eat and die of hunger. Then, the ecosystem would be off balance.

"If the number of insect species keep dropping, this will have bad influences on both Earth's ecosystem and the survival of us humans," said one of the writers of the review.

"The first step to stop this is to let more people understand the values of the natural world," he suggests. "The best place to start is from our children, who should realize environmental protection from an early age."

     When you are planning for a travel alone, you might need to work out a plan. Sometimes a good journey will give you the most fun at the least cost. The advice below might help you save money on your travels in China.

     Usually, you will pay quite a lot of money on all kinds of transport. Travel by train if you have enough time. You can save a lot in this way. From Chongqing to Beijing, a round-trip flight ticket costs about 2,800 yuan, while a round-trip train ticket costs only 800 yuan.

     It is also important to choose the most proper transport after you have arrived at your destination. But do you choose to take the city buses or taxis if you want to go to the places you want to visit? A good suggestion is to buy a map and draw the most proper transport route.

    The hotel can also cost a lot if you do not have good choices. A good way is to book your room through a travel agent or an Internet travel service before you start travelling.

     It is easy to buy whatever you want in China. You can buy a large number of souvenirs in large stores or shopping malls in China. If you want to shop for souvenirs to take home, you can look around in some of the open markets because the prices there are much lower. Your local travel guides are the best help when you go to these places.