Spiders are not insects as many people believe. They belong to a class of animals called arachnids(蛛形纲动物). Spiders have eight eyes, four pairs of legs, and can grow a new leg if they lose one. A spider's body is divided into two sections: the abdomen(腹部) and the thorax(胸部).The legs, eyes, and mouthparts are in the thorax section.

    Most spiders have poison glands(毒腺)and sharp teeth. They use their sharp teeth to force poison into the insects they catch for food. This poison can make an insect lose the ability to move, and the helpless insect is then devoured by the spider.

    Spiders usually have silk glands under their abdomen. They produce a liquid(液体)that is thicker than water from their glands. When the liquid comes into the air, it dries into silk. Many spiders use this silk to form webs to catch insects and to make cocoons(茧)that protect their eggs. This amazing silk is also used to create lines that spiders hang onto as they travel to new areas.

    Spiders live in almost everywhere on earth. The only places where there are no spiders are the coldest places, the highest mountains and the seas.

Smog is a big problem in many Chinese cities. But it seems that besides wearing a mask, few of us know what has caused the smog and what to do to beat it. In fact, burning too much coal and oil are the main causes of PM2.5 and smog (雾霾).

    To solve the problem, we should clean our coal and oil or replace them with cleaner energy such as natural gas. We ordinary people can do something to help control smog, too.

    What can we do to help beat the smog?

    Choose to take public transportation. Though many people have their own cars, they had better take public transportation, such as the subway or buses. If the destination (目的地) is not far away, you can also walk ________ ride a bike.

    Call the hotline 12369. You can call the number for complaints and questions about environmental issues. It is run by China's Ministry of Environmental Protection. If you call the number, some officers can come and try to solve the issues, so please remember it.

Report and resist pollutant source. If you find any pollutant source, take a picture of it and post it on your social media accounts. Remember to add “@local environmental departments” on weibo. Payattention to factories that pollute the environment and don't buy products from them.

    Our environment will become better if everyone is concerned (关注) with the environment. This is what we need in the future. So everyone can do something to beat smog.

    Many environmental groups are warning that oceans of the world are in great danger. In the past 50 years, the number of water with zero oxygen(氧气) in the open ocean has increased more than four times. In the near coast water bodies, including the river mouth and seas, low-oxygen areas have increased more than 10 times since 1950.Scientists discover that oxygen continues dropping ever outside these zones as the Earth warms. To stop the drop, the world needs to control in both climate change and nutrient(养分) pollution.

    Oxygen is a must to life in the oceans. The drop in ocean oxygen is among the most serious effects of human activities on the Earth's environment.

    This is the first time for the scientists to take such a deep look at the causes, results and solutions to low oxygen worldwide, in both the open ocean and the near coast waters. About half of the oxygen on Earth comes from the ocean. However, mixed effects of nutrient loading and climate change are greatly increasing the number and size of "dead zones" in the open ocean and the near coast waters, where oxygen is too low to support most sea life.

    In the areas traditionally called "dead zones", like those in Chesapeake Bay and the Gulf of Mexico, oxygen drops to levels so low that many animals have trouble in breathing and die. As fishes run away from these zones, their living areas become smaller and smaller. But the problem goes far beyond "dead zones". Even smaller oxygen drops can hold up the growth in animals and lead to disease or even death. Low oxygen also can cause the release of dangerous chemicals. Although a few animals can grow well in dead zones, overall biodiversity(多样性)falls.

    Technology is everywhere. In fact, almost all of us carry a certain piece of technology with us every time we leave the house. What I always forget, though, is just how useful and powerful technology can be when we want to help others.

    There is not a single room in my house that does not have some electronic devices(设备).Whenever I am at home, I am almost always using at least one electronic device. If you walk into my living room on any given day, you will find that, first, I have the television on. At the same time, I usually have my laptop resting on my knee, or I am using my mobile phone. Even when I'm not at home, I am always using my phone, and at work or in cafes, I sit down and connect to the local wireless network on my laptop.

    I must say that I waste a lot of time on the computer and the time I spend on it could be much better spent if I were to take up a little online volunteering.

    Recently I discovered just how much online volunteering there is to do in the world. From using your language skills to do translations, to developing and managing projects and helping with IT work, there is so much that so many people can do to help people in their own countries and across the world. The United Nations, in fact, has a huge page with "Volunteers Recruited" on its website.

    This work can support the poor and help charities who cannot pay for staff members. Many organizations only require you to work an hour a week, some even less. And the support provided by online volunteers can really help make a difference to those in need.