B

    Have you ever wondered why the roots of the plants always know which way to grow—into the soil but not above it? Some British scientists have recently solved this mystery.    

      It turns out that roots have special hairs that tie them into the soil and help them grow their way past obstacles, a team at the John Inners Center in Norwich reports in the February 29 issue of Journal Science.

    "The key is in the fuzzy(有绒毛的) coat of hairs on the roots of plants," says professor Liam Dolan. "We have found a growth control system that enables these hairs to find their way and to become longer when their path is clear."

    Root hairs explore the soil in much the same way a person would feel their way in the dark. If they come across an obstacle, they make their way around until they can continue growing in an opening. I the meantime, the plant is held in place as the hairs grip the soil.

    The hairs are guided by a clever chemical trick. A protein(蛋白质) at the tip of the root hairs called RHD2 helps them to take calcium(钙) from the soil. Calcium makes the hairs grow, and produce more RHD2, and take more calcium.

    But when an obstacle blocks the hair's path, or the hair reaches the surface of the soil, the cycle is broken and growth starts in another direction.

    This system gives plants the flexibility to explore a complex environment and to live in even the most unpromising soils, says Dolan.

    In poor soils such as in parts of Australia and Africa, native plants have adapted by producing enormous numbers of root hairs. A better understanding of this adaptation will allow scientists to develop hairy rooted crops that can grow in unfriendly environments.

    According to Dolan, "Research in the John Inners Center is taking a breeding approach(育种方法) to increase hair length in wheat but it will be some time before new cultivars(栽培变种) are developed."

    In high school, all Canadian students take part in a very exciting event. It is "Take Your Children to Work Day". Students will have a chance to work with their parents. My day took place in my mom's work, the York Region Police Department.

    When I arrived, a coach was teaching the officers basic combat(格斗)skills. Everyone tried their best to practice. I could see them sweating and panting (喘气).

    The most exciting part of my visit was a stop at the 911 Communication Center. 911 is the same as 110,119 and 120 in China. Every 911 call in the city is answered here. When I entered the center, I stood beside a call dispatcher (分派人员)arid watched him dealing-with the calls.

    Suddenly, the phone rang, he picked it up and a woman cried for help. There was a robbery in her house. The call dispatcher told her, "Please calm down and move to the safe place quietly. Don't fight with them. Just let them take what they want. Please make sure you are not hurt. We are sending officers there."

    He followed the call and found the address. The call dispatcher chose the five closest police cars from the satellite map and clicked(敲键盘) to send the policemen.  I saw the police cars from the satellite map were quickly moving to the woman's house. Five minutes later, they arrived .I asked the call dispatcher why he sent five cars. He said, "There are different levels of emergencies. Robbery is a high priority (优先),so we have to send five cars." The day was interesting. I leaned how the different departments worked together. The officers were very friendly and admirable.

    The English language has many ways to talk about something that is funny. {#blank#}1{#/blank#} It is a basic human need. Physical humour, especially, can cross limits like nationality and language and bring people together from all different walks of life.

    Humour comes in many forms. The most obvious and traditional way we use humour is in jokes. {#blank#}2{#/blank#} This is when a person changes a word or uses it in a different context(上下文) for comic effect.

    Another way people can use humour is through telling a funny story. Perhaps something bad happened to the person but they can laugh about it now. People also invent funny stories in order to make people laugh. The advantage of this is that the characters aren't real. {#blank#}3{#/blank#} 

    Physical comedy usually divides opinions. For some, seeing someone fall down, whether it is planned or not, is one of the funniest things they can see. {#blank#}4{#/blank#} Some types of humour can also be harmful if someone is not in the mood for being made fun of！People's senses of humour vary across the world, so what may be funny in your country might be incredibly harmful in another!

    {#blank#}5{#/blank#} The British, for instance, are famous for their humour in English. However, people learning a foreign language face much difficulty when it comes to being funny in a second language.

A. Humour is just one of the ways.

B. Everyone needs to laugh once in a while.

C. Other forms of humour are word play and puns(双关语).

D. Therefore, you don't have to feel bad for laughing at them!

E. People of all ages and cultures have a strong sense of humour.

F. Most people know how to use some form of humour in their native languages.

G.For others, finding physical humour and non-serious accidents funny seems cruel.

    Lots of people buy books and products from Amazon, an online seller. They offer and pay over the Internet and the books are shipped through the mail or a delivery service like FedEx.

    One day, people could get their Amazon deliveries from an “unmanned aerial vehicle”—a timely vehicle that looks like a toy helicopter. And instead of waiting days to get the parcel, it could be at the buyer's home in half an hour or less. The company is working on a fleet of tiny vehicles they call “Prime Air”. The vehicles are also known as “octocopters”. On their website, Amazon says, “One day, Prime Air Vehicles will be as normal as seeing a mail trucks on the road today.”

    The U.S.'s Federal Aviation Administration (FAA) is working on safety regulations for unmanned flying vehicles like the Prime Air copters. Those regulations will make sure the copters are able to fly safely where they need to go. Once the FAA has put its rules in place, which could be as early as 2016, Amazon will be ready with its fleet of tiny flyers. The process could take as many as five years.

    The new delivery service would likely be available only in the United States, at first. The copters the company is testing now can handle packages up to five pounds (2.3kg) and they have a range of 10 miles (16 kilometers).

    Other companies are also looking at using unmanned flying vehicles to deliver their products. For instance, Domino's Pizza in the U.K. released a video showing a “DomiCopter”, delivering a pizza. That video may have been a publicity stunt（噱头）. In any case, just like Prime Air's octocopters, the DomiCopters don't have clearance（许可）to take off just yet.

My grandfather was born in a small town in Italy. He would wake up at four in the morning every day to work on the farm. Although he was a great student in school, he only went up to Grade 3 because he was required to help with the family farm. 

Later, my grandfather used his own hard-earned savings—the small amount was all he had—to travel to Canada. He was alone in a new country, not knowing anyone and not speaking English or French. At a farm, the owner quickly saw what a hard-working young man my grandfather was, so he paid my grandfather a much higher salary. Although the owner was very nice to him and treated him like family, he was not satisfied. He dreamed of being more successful, of better career advancements. 

One day, he got an offer to work in the construction industry. My grandfather, a newly immigrated young famer, who was eager to move up in the world, caught this opportunity and prospered( 发达 ) through hard work. Around 1967, however, he become overwhelmed(不知所措的)with stress, sleepless nights and anxiety from the business. He also had two young daughters to take care of and my grandmother was in the hospital at the time. The combined stress and anxiety unfortunately drove him into a major depression. During a medical check-up, his doctor warned him about his health. He knew it was time for him to make a change and decided to sell his shares in the company. 

He then began a smaller business of his own, which resulted in less stress and more time with family. Had he chosen not to quit his former job, he might have been a billionaire today. My grandfather will turn 95 in October; even at this ripe old age, he is still strong, well and high-spirited. Looking at his story as a life example, he teaches us to work hard, but at the same time not to forget to enjoy life and have a good sense of humour about it all. 

Work is important, sure, but there is much more to life than just that. Overall, this is the ultimate key to happiness. 

Robots have long been drawing inspiration from animals, with the creation of robot dogs or snake-shaped robots. And yet, the field of robotics is far less enthusiastic about the other kind of living things—plants. Barbara Mazzolai, an Italian roboticist owes this to a misconception about plant behavior: that they cannot move or think. "It's not true at all, " she says. To challenge this view, Dr Mazzolai and her team recently launched a machine called "FiloBot", a robot based on a climbing species. 

To survive, a climbing plant must switch between several different behaviors. In forest environments, it must first grow out of the soil and travel along the ground in search of a support to hold onto, such as a nearby tree. Once a support is located, though, the plant fixes itself around the object and then growing towards the light. To choose the best angle to grow upwards, a climbing plant uses its shoots(芽) to receive information about light and gravity. 

FiloBot has sensors on its main shoot. It can 3D-print its body with plastic and grow at a controllable rate. These functions, researchers found, enabled FiloBot to cross gaps, and find things to attach to. The lack of heavy on-board computing device means that it is light and requires minimal care, while its slow pace means that it doesn't disturb things around it, making it possible to move through a complex, unseen environment, or monitoring disaster sites. 

For now, FiloBot is still being tested. Its tendrils(卷须) have not left the laboratory. Still, it has already been employed in deconstructing plant behaviour. For example, it was long assumed that climbing plants find their supports by growing towards shade, though the exact mechanism was unclear. FiloBot could imitate this behaviour by detecting far-red light, which is typical of shaded areas, providing clues to how plants do it. 

Dr Mazzolai hopes that such projects will inspire other roboticists to take their cues from plants and develop completely new technologies.