Books are for reading, but man must bring to their reading a desire to learn and a power of absorbing. Reading should be active, not passive.

    When students first go to a library, they may be at a loss as to what to read of all the different subjects. Well, Bacon tells you to “look at weak places in your armor(盔甲)”, and shows you how to fill up the blanks in your knowledge. On the other hand, it is no good just trying to fill your mind with knowledge. Knowledge in itself is often useless. A mind filled with too much knowledge is like a room too full of furniture; a man cannot walk about freely in it, and look out of the windows. It is much better to concentrate on a few subjects which interest you and to deal lightly with the others than to march heavily through the whole range(范围) of learning, like a silly tourist going through a museum and not missing a single object. If you try to master every subject you may become very wise, but you will be very lonely and you will probably lose all your friends. So you must learn to pick and choose, and you must also learn to look here and there in a library like a camel eating grass on the grassland. If you watch it eating, you will see that although he is supposed to be one of the most stupid animals in the world, he has at least one of the qualities of the cultured man, the power to pick and choose. A student looking for mental food in a library should take the camel as his model.

    We have to admit that many cities around the world today are heavily polluted. Careless methods of production and lack of consumer demand for environment friendly products have actually contributed to the pollution problem. One result is that millions of tons of glass, paper, plastic, and metal containers are produced and these are difficult to get rid of.

    However, today, more and more consumers are choosing “green” and demanding that the products they buy should be safe for the environment. Before they take action to buy a product, they ask questions like these “Will this shampoo add damage to the environment?” “Can this metal container be reused or can it only be used once?”

    A recent study showed that two out of five adults now take the environmental safety of a product into account before they buy it. This means that companies must now adjust the way they make and sell their products to make sure that they are “green” that is, friendly to the environment

    Only a few years ago, it was impossible to find green products in supermarkets, but now there are hundreds of them advocating green. In addition, some supermarket products carry labels (标签) to show that the product is green. Some companies have adopted the manufacturing (生产) of clean and safe products as their main selling point and emphasize it in their advertising.

    The concern for a safer and cleaner environment is making companies rethink how they do business. No longer will the public accept the old attitude of “Buy it, use it, throw it away, and forget it.” The public pressure is on, and gradually business is cleaning up its act.

    This year's flu season is pretty scary. To try to minimize the effects, public officials are still urging anyone who hasn't yet gotten their flu shot to get one as soon as possible. However, even if every single person got a shot in the arm, the vaccine(疫苗)—with its excellent 36 percent effectiveness—would not prevent everyone from getting infected with the annoying virus. Knowledge is power, so here's what goes on in your body when you come down with the flu.

    The influenza virus primarily attacks your nose, throat, and the tubes that lead to your lungs. But the flu is so much more than that. Your muscles ache, your head hurts, and your appetite goes down, among other things. To our surprise, almost all of these symptoms have less to do with the virus itself than with your immune(免疫的)response to them. Unfortunately, the very defense you have in place to get rid of the flu is the reason you feel so painful when you recover.

    The virus usually enters through your mouth, typically by way of your hands But it takes a few days for symptoms to set in. While this process might cause some harm to your nose and throat, it's nothing major, and nothing like the symptoms that typically accompany a bad or even mild case of the flu.

    The real fun starts when your immune system begins to fight. Your immune system comes in two parts: the innate system and the adaptive. The innate immune system is essentially an all-purpose tool. As soon as your body senses the presence of any injury or invader (入侵者), the innate immune system launches into action by producing tiny proteins called cytokines and chemokines. The cytokines reproduce almost immediately and start to attack the virus. This increase in immune cells creates an serious inflammation(炎症) throughout the body. But the worst is still to come. Meanwhile, the chemokines work with the adaptive immune system to help create T cells. These cells are a special type of white blood cell that works in a much more specific way: They find the influenza virus, identify what's special about it, and create something unique on their surface that finds and destroys similar invaders.

    As free as they make us, mobile phones still need to stay close to a power source. Soon that may change with "green" power.

    Three Chilean students got the idea for a plant-powered device(装置) to charge（使……充电） their cellphones, while sitting in their school's outdoor courtyard during a break from exams, with dead mobile phones. Then, one of them had an "aha" moment.

    “It occurred to Camila to say about plants,” said inventor Evelyn Aravena. “'Why don't you have a socket, if there are so many plants? 'After that, we thought, 'why don't they have a charging outlet（插座）? Because there are so many plants and living things that have the potential to produce energy, why not?'”

    Their invention—a small biological circuit called E-Kaia—uses the energy plants to produce during photosynthesis(光合作用). A plant uses only a small part of that energy and the rest goes into the soil, and that's where the E-Kaia collects it. The device plugs into the ground and then into your phone.

    "It's the most amazing project I've ever seen in my life, plain and simple. They brought this original model, and it worked — and that's when it all changed, at least from my personal point of view and I began to support them." said Mauricio Cifuentes.

    The device solved two problems for the engineering students — they needed an idea for a class project, and an outlet to plug in their phones.

    "Looking for a place to charge the notebook, which had no power, and the mobile phones, we weren't able to find anything because all the other students were in the same state of madness trying to find a place to charge their devices," said Aravena.

    But plants are everywhere, and the bio－circuit makes good use of their excess(过多的) power.

    The E-Kaia doesn't carry much charge but it's powerful enough to completely recharge a mobile phone in less than two hours.

    The student inventors have applied for patents（专利） on their technology, and expect the E-Kaia to go on sale in the near future.

    In the online world, it's very difficult to talk to Chinese people without using emojis. However, did you know that people in different age groups have totally different preferences for choosing their emojis? The result is based on a report released by Tencent's WeChat, China's most popular messaging app, on its official weibo account on Wednesday.

    Specifically, for users who were born in the 2000s, their favorite WeChat emoji would probably be the widely used "facepalm", rumored to be based on the famous Hong Kong movie star Stephen Chow. They also may be a night owl without much sleep, while iced beverages and desserts are their cup of tea.

    For China's post-90s WeChat users, they are likely to get out of bed later in the morning compared with other groups, and the emoji "face with tears of joy" may rule their online social life. Also, their reading materials have shifted from entertainment and gossip three years ago to the current relationship and lifestyle pieces.

    For those born in the 1980s, their tastes have remained the same, as they are still fond of reading news on national affairs. And "smiling widely" is their emoji of the year.

    WeChat users born in the 1970s are called the optimistic group, who like to use the emoji "laughing quietly" and go through their moments frequently every day. Their bed time usually takes place around 11:30 pm.

    Users over 55 are the early-bird group with rich entertainment activities in WeChat platforms, such as looking through moments, reading and shopping. They like to cheer up other age groups, so their favorite emoji is "giving a thumbs-up".

    The report also indicates that WeChat boasts more than 1.08 billion active users with 45 billion messages being sent and 410 million calls getting through the app each day in 2018. In addition to covering users' socializing, WeChat has gradually come into our daily lives. Compared to the year before, people used WeChat 4.7 times more to purchase public transport tickets, and 2.9 times more to pay for medical expenses. Also, the app was used 1.5 times more over the previous year to pay for meals, with Beijing, Guangzhou and Shenzhen ranked as the top three cities in dining purchases through WeChat.

The huge billboard at the side of the highway is no joke; transporting firewood in certain areas is a crime, punishable by a four-thousand-dollar fine. The reason? Emerald Ash Borer disease, or EAB disease, a new addition to the long list of dangerous foreign pest infestations（虫害）on American soil. It was in 2002 when the Emerald Ash Borer beetle（甲虫）was first discovered in Michigan. Not long after, the pest was found in Ohio. Originally from Asia, this green beetle probably found its way to North America through a wooden box made of ash wood and immediately settled into a local ash tree. In little time, the species managed to kill millions of ash trees. 

To date, much work is underway to stop ash trees ending up in the same group as elm and chestnut trees, which are all dying out in many areas. Ash Borer Infestations are particularly troublesome because they are difficult to identify until the ash tree is heavily infested. In addition, other ash trees in the area surrounding the source will probably also be infested, making control a hard task. 

Researchers are working on many issues related to the control and removal of this harmful beetle. For example, it has been discovered that Asian ash trees are not destroyed by this native borer. It may be that, Asian ash trees have developed genes（基因）to protect them from the insect; therein, perhaps, lies the secret to controlling this pest. Insecticide（杀虫剂）treatment is also being explored on several fronts. Research is underway to determine which insecticides are proving to be the most successful. The proper application of the insecticides is being debated. 

However, all possible solutions require a great deal of study and research. In the meantime, careful steps must be taken. Methodical identification of infested trees is taking place. Identified trees are being cut down and destroyed to get rid of the beetle colonies（群）. In the end, this puts a huge drain（消耗）on city budgets, as tree removal can be extremely expensive. 

Even though it will be expensive to deal with this problem in the short term, the costs of doing nothing could be far higher, since we could lose an entire species of tree.