Have you ever planted a few trees on Tree Planting Day? Each year, millions of people, both 1, plant a lot of trees. But this may not be the best way to make your home 2.

    Last week we visited a park in Hebei. We were  3 to find most of the trees had been burned. The workers told us that the trees  4 soon after they were planted because they weren't watered well enough. 5 workers burned them and cleaned the place for 6 trees to be planted this year. 7 a card found in one of the dead trees, a student wrote, "I hope this tree will grow up with me to  8 the backbone(栋梁) of our country." The workers said that the survival(存活) of the trees was really more important than 9 trees were planted.

    Some people in Beijing now have a new idea that they can donate(捐赠) some money and let professional (专业人士) plant and 10  the trees.

    When you go out for a business trip or weekend, you have to 1 pack your mobile phone, laptop(手提电脑), MP3 player, camera and so on. It's wonderful for you to 2 no batteries, no chargers(充电器) and no wires.

    This is the future “wireless power”. That is 3 of passing on electricity through the air to laptops and other small electrical devices (装置) without the need of wires.  These new devices were4 the first trade products in Las Vegas at the International Consumer Electronics Show, the world's biggest trade 5 for small electrical devices.

    Experts believe this is just the 6. In a world without wires, you can use a laptop in cafes or airports 7 you put an “electricity hotspot” inside and no longer have to search for a charger form your bags. It is said that you will be able to 8 your devices in the room that has wireless power, and then they will get the power 9. If one room has wireless power, you would know that once you walk through the front door, your mobile phone starts charging up, even when it is still in your bag or pocket. You'd never need to 10 the right charger again.

    This kind of technology, named Power Bean, can turn electricity into a laser(激光), then pass it on as heat, across the room.

    Workers aren't allowed to go into a big underground computer center until they step up to a machine that takes a quick picture of the tiny blood vessels (血管) inside their eyes.

    If the machine can't 1 the picture with images in its computer, the worker is stopped by security guards (保安员).

    Each person has his own way of blood vessels in his or her2.And unlike a key, the way can't be3.Old-fashioned keys and locks may soon be things of the past.High-tech security devices (安全装置) are being fixed at military (军事的) bases, computer centers and banks.Companies that 4 the machines say they'll someday be used in people's homes and cars.

    Already, a Japanese company has fixed ways that recognize (识别) people's fingerprints in 360 new homes.The machines open the doors only for the 5of the houses.The new security ways are selling well because thieves and robbers are getting better at breaking into buildings and computers that are 6 by keys and locks.Since nobody can steal or copy a fingerprint, or one's eyes, the new machines are 7.

    Other new machines recognize one's voice.Two American companies use 8 machines to keep an eye on their computers.Inexpensive voice-recognition machines may someday take the place of locks on cars.The doors would open only for the owners.The machines would 9 the owners as little as $270.Although the up-to-date machines are amazing, scientists must still solve a serious problem.How will a boy borrow his dad's car without borrowing his dad's 10?

    March 22nd is World Water Day. It started in1993. It not only makes us think about the importance of water, but also calls on(号召）us to1and protect water. Today, we're facing terrible water problems. Among them, wastewater problem is especially 2. And the subject of World Water Day in 2017 is "Wastewater".

    What is wastewater? It is used water. Usually, wastewater comes from homes, 3, hospitals and so on. It is produced by different kinds of activities, including washing the clothes, taking showers and using the kitchen. The rain also4 wastewater when it is running down the street during a storm. No matter where it comes from, this kind of water is sure to have5harmful in it.

    6must we treat（处理）wastewater? Wastewater has a big influence on our life. It causes both illness for us and pollution for the environment. We must care for our environment and our own7.

    How can we treat wastewater? Different kinds of wastewater need different ways of treatment. Wastewater8 homes can be reused. Then there will be9 wastewater. Also, factory wastewater has to be cleaned 10 it goes back to nature.

    Nowadays many people are talking about aliens. You might see them 1.

They are very smart, but they look 2. They travel in spaceships.

    But are there really aliens in space? British scientist Stephen Hawking, thinks so. He says that people 3 look for aliens. He thinks they are dangerous.

    On a British TV programme, Hawking says, "It is 4 that there are aliens in space."

    "They might live in big ships. They have 5 all the resources(资源) from their home planet." he says.

    He thinks such aliens might get resources from Earth and then go away. They may bring 6 to the Earth.