1 . Want to know what we can do to help make our city a better place to live in? Why not take part in “Clean & Green weekend”? Join us, and you can make new friends and help protect the environment at the same time.
Park Life
Do you like playing and relaxing in the park with your friends? If so, why not take the chance to come with us and tidy up the park when you go? To add some fun, there is a gift for the person who collects the most rubbish! Meet us at the south entrance to Taohe Park at 9 a.m. next Saturday if you want to join in.
The Air You Breathe
A great way to make the air we breathe cleaner is by planting lots of trees！It is a fact that trees slowly filter (过滤) a lot of pollutants (污染物) from the air. So come and help us plant some new ones in Fenhe Park at 2 p.m. next Sunday.
War on Graffiti(涂鸦)
Some people think graffiti is cool. Well, it is not! The best way to stop buildings from becoming totally covered in ugly graffiti is to fix it as soon as possible. And that is exactly what we are going to do. We are repainting the school walls from 1 p.m. on Saturday. You don’t have to bring any tools, just remember to wear some old clothes!
1. The main purpose of “Clean & Green Weekend” is to ________.| A．have a nice weekend | B．offer the chance to have fun |
| C．help students meet old friends | D．make our city more beautiful |
| A．draw pictures well | B．bring some tools with us |
| C．wear some old clothes | D．wear some new clothes |
| A．on a school notice board | B．in a fashion magazine |
| C．in a travelling magazine | D．on a hospital notice board |
2 . Being trapped in an elevator(电梯) can be one of the worst experiences of one’s life. Some people who have such experiences may be afraid to use elevator again. In fact, there are some useful tips to follow when people are in trouble with the elevator.
First, take deep breaths and keep calm. Too much fear will add to your panic(恐慌) and make you too nervous to think clearly. Tell yourself to be patient and believe that nothing is impossible.
Secondly, use the emergency(急救) call inside the elevator or your mobile phone to let people outside know your are stuck in the elevator. There is an emergency call on the wall of each elevator. You may use your mobile phone to give light and find it. The phone number can be found around it.
Thirdly, putting on messages on Wechat(微信) is also a good idea to allow more people to find you are in need of help. If help hasn’t come, knock the door hard to get attention from other people in the building.
Fourthly, move less and try to relax. Even if the workers have known your situation, it may take them a long time to repair the elevator and bring you back to safety. Instead of keeping moving all the time, you are advised to keep still and relax yourself as much as possible, or you will make yourself tired out. Make sure that you are fine when the door is open.
1. According to the passage, when in trouble with an elevator, you should________ first.| A．Keep calm and think clearly | B．do nothing but wait |
| C．shout out for help | D．try to break the door open |
| A．tired | B．kept |
| C．troubled | D．trapped |
| A．they can spend their time easily |
| B．their situations can be known by more people |
| C．they can become less nervous |
| D．they can make more friends |
| A．To introduce how to use an elevator. |
| B．To teach us how to save ourselves when trapped in an elevator. |
| C．To warn us not to take an elevator. |
| D．To tell us an elevator often goes wrong. |
3 . China's historic 23-day Chang'e 5 mission has not only obtained precious rock and soil samples from the moon, but has also brought back a group of seeds that traveled the furthest in the nation's agricultural and forestry histories. More than 30 kinds of seeds, including that of rice, oats etc., were placed inside the multi-module Chang'e 5 spacecraft and orbited around the moon for about 15 days.
Scientists wished to check what would happen to the seeds after being exposed to extraterrestrial (地外的) forces in lunar orbit and also hoped that they could develop beneficial mutations (突变). This mission offered good opportunities to scientists, which enabled them to deepen their studies on the effect of cosmic rays on the growth and evolution of life on Earth.
Space-based mutation breeding refers to the process of exposing seeds to forces such as microgravity, vacuums and cosmic radiation during a spaceflight and then sending them back to Earth for further observation and planting. Researchers observe and examine several generations of plants grown from space-bred seeds and investigate their mutations-some are positive and desirable while others are negative. Those with positive mutations will be kept and analyzed, and will be introduced to farmers after their certification and approval.
Space breeding can generate mutations faster and more conveniently than ground-based experiments and can bring about some desirable traits that are otherwise hard to introduce. Compared with natural or conventionally bred types of plants, space-developed versions with positive mutations usually feature higher nutritional content, greater annual yields, shorter growth periods and better resistance to diseases and insect pests.
China conducted its first space breeding experiment in 1987, using a satellite to carry seeds into space. Since then, hundreds of kinds of seeds and seedlings have traveled with dozens of Chinese spaceships. Space breeding has helped to produce more than 200 new types of mutated plants in China that have been approved for large-scale cultivation, ranging from grains to vegetables and fruits. The Chang'e 5 robotic mission returned 1,731 grams of lunar rock and soil to Earth, marking a historic accomplishment 44 years after the last lunar substances were taken back.
1. Why were the seeds placed inside Chang'e 5?| A．To pick out the fittest for mutations. | B．To understand extraterrestrial forces. |
| C．To study the intensity of cosmic rays. | D．To expose them to a special environment. |
| A．It is not a time-consuming process. | B．Mutations develop in a random way. |
| C．It often brings about desirable effects. | D．Approval will be granted to mutated plants. |
| A．It is a custom to put seedlings on a spacecraft. |
| B．China was the first to do a space breeding experiment. |
| C．It is some time since seeds were last taken into space. |
| D．Space breeding has brought us commercial benefits. |
| A．Space-bred Seeds Offer Great Chances | B．Chang'e 5 Returns with a Big Package |
| C．Plant Mutations Result in a Better Life | D．Seeds from Space Mark a New History |
4 . I bought several packs of seeds, 24 small plastic seed pots, plant fertilizer and potting soil. I made sure the soil didn't contain added fertilizer. I wanted something that I could grow quickly, that wouldn't take up a lot of space and that wouldn't get too big. I ran this experiment in early fall in Maryland. So I knew I needed a plant that could grow when it's cool. I picked radishes (小萝卜), which grow well in the early fall or spring. Some varieties can grow a full radish in only 21 days.
I kept 12 of the pots and one pack of seeds for myself. I gave the other 12 pots and the other packet of seeds — along with some fertilizer and soil — to my editor, Sarah. This was to provide an additional control for location. After all, what if my yard just happens to be much better for growing plants? What if it's worse? By dividing the plants up between my yard and Sarah's, I hoped to make sure that any difference with the plants came from the fertilizer.
Sarah and I planted our seeds. Sometimes, seeds don’t sprout (发芽). So we carefully planted four evenly (相等地) spaced seeds in each pot. Six of my pots (and six of Sarah’s) served as controls — pots that would not get fertilizer. Our other six were treated with fertilizer. For each of us, this added up to 24 control seeds, and 24 seeds that would get fertilizer.
We watered all the plants equally with clean water every other day (unless it rained). Once a week, we applied fertilizer to half the pots. We also took pictures every day, so we could see the plants change over time. As I expected, many of our seeds didn't sprout. In fact, only about a fourth of mine sprouted. Sarah has a greener thumb. She successfully grew half of hers.
1. Why does the author want to grow such a plant?| A．To enjoy it. | B．To make it very cool. |
| C．To take up more space, | D．To make an experiment. |
| A．From the fertilizer used. | B．From the different way. |
| C．From the different soil. | D．From the seeds used. |
| A．The experiment is successful. | B．The author is respectful to her editor. |
| C．The author is considerate. | D．The process of the experiment is complex. |
| A．She's fond of growing plants. | B．She's smarter than the author. |
| C．She has a gifted for growing plants. | D．She's a devoted and friendly woman. |
5 . Researchers at CU Boulder have developed a wearable device that changes the human body into a biological battery. The device is stretchy(弹性的) enough that you can wear it like a ring, sport band or any other thing that touches your skin. It also taps into a person's natural heat-employing thermoelectric generators to change the body's internal temperature into electricity. "In the future, we want to be able to power your wearable electronics without having to include a battery," said Jianliang Xiao, an associate professor at CU Boulder.
The concept may sound like something out of The Matrix film series, in which a race of robots have enslaved humans to harvest their precious organic energy. Xiao and his colleagues aren't that ambitious: Their devices can generate about 1 volt (伏特) of energy for every square centimeter of skin space-less volt per area than what most existing batteries provide but still enough to power electronics like watches or fitness trackers.
Scientists have previously experimented with similar wearable devices, but Xiao's is stretchy, can heal itself when damaged and is fully recyclable-making it a cleaner alternative to traditional electronics. "Whenever you use a battery, you're depleting(消耗) that battery and will, eventually, need to replace it," Xiao said. "The nice thing about our device is that you can wear it, and it provides you with constant power."
Just pretend that you're out for a jog. As you exercise, your body heats up, and that heat will radiate out to the cool air around you. Xiao's device captures that flow of energy rather than let it go to waste. "The thermoelectric generators are in close contact with the human body, and they can use the heat that would normally be sent into the environment," Xiao said.
1. What does Xiao expect of his device at present?| A．It will be used for medical purposes. |
| B．It will be made smaller and wearable. |
| C．It will change natural power into electricity. |
| D．It will supply constant power to wearable devices. |
| A．To give an explanation. | B．To make a comparison. |
| C．To introduce a topic. | D．To analyze the cause. |
| A．The strengths of Xiao's device. |
| B．The convenience of using a battery. |
| C．The replacement of wearable devices. |
| D．The development of traditional electronics. |
| A．It operates with plenty of power. |
| B．It is designed for practical use. |
| C．It benefits people's health in a way. |
| D．It's based on traditional electronics. |
