【答案解析】1. As the first picture suggests, we should always turn off a tap completely after we use it. Or else, 20 liters of water will be wasted in one day. In this way, as much as over 7000 liters of water will be wasted in one year. Water is a natural source that costs much to be recycled. Many people let water drip and do not care. They think it has nothing to do with them. Actually, this is very wrong. Everyone has the duty to avoid waste and make the economical use of water.
2. The second picture tells us the serious problem of using disposable chopsticks. As you know, such chopsticks are made of wood. When we go to restaurants or dining-halls, we often use disposable chopsticks for convenience and the so-called sanitation. But this is a great waste of wood. The forest in China is now destroyed seriously and is very difficult to resume. If everyone uses this kind of chopsticks for meals, how many trees would have to be fallen down each year?
3. The third picture shows us plastic bags cause much pollution. In recent years, with the development of economy, pollution, especially the "white pollution" becomes more and more severe. For convenience, we often use plastic bags in shopping. Though convenient, plastic bags are difficult to be recycled, and they can pollute the soil and water. When burnt, they pollute the air and release poisonous gas. Thus, we must reduce the usage of plastic bags and try to protect our environment.
4. The fourth picture shows cars cause much pollution. With economic development, more and more people buy cars, but the gas cars produce pollutes the air a lot and greatly harms people"s health. The best way to solve the problem is to use new kinds of fuel that cause no pollution, but it can"t be realized now in most countries. But we can use some high-tech devices to reduce the gas and to clean some harmful pollutants in it. Car factories should produce these kinds of cars and the government should also control the amount of gas produced by cars.