All sorts of items become litter(垃圾) but two of the most common and most dangerous are cigarette butts（烟头) and plastic bags. Litter is a big problem for our environment but it is a problem that individuals can easily do something about. Not littering at all or cleaning up litter, such as  cigarette butts and plastic bags, greatly improves the quality of our environment. Although cigarette butts, are small, they are bad for the environment. Over 1,600 billion cigarette are smoked each year in China and large quantities of the butts are thrown away. Worldwide, about 4. 5 trillion butts are littered every year. Apart from the fact that butts spoil the beauty of the environment, they contain some very toxic chemicals. These find their way into the water supply where they decrease the quality of the water and endanger plants and animals that live there. So, if people have to smoke, they shouldn't throw away the butts but put them in the rubbish bin instead. Plastic bags are another common form of litter that is a danger to the environment. There areseveral reasons for this. They are made from oil and gas, which are non—renewable resources. If they are not recycled, these resources are lost to us. In China, 2 billion plastic bags are used every day. An enormous number of these become litter. This is a huge problem because they last from 20 to 1,000 years in the environment. They float easily in the air and water and travel long distances. They find their way to rivers, parks, beaches and oceans. Plastic bags kill up to one million seabirds, 100, 000 sea mammals and countless fish each year worldwide. It is up to people not to let plastic bags become litter. It would be better if they used fewer and recycled them. Cleaning up your cigarette butts and plastic bags would improve the environment. And we would know that we were doing something to look after our planet. However, I believe the best solution would be not to smoke or use plastic bags at all. 小题1: Which of the following best shows the structure of the passage? A           B.         C.          D. ( ①=' paragraph' 1; ②=' paragraph' 2; ③=' paragraph' 3; ④a para graph 4 ) 小题2:The word “toxic” in the paragraph 2 most probably mean “________” A．precious B．extra C．poisonous D．useless 小题3: From the text. we know the fact that_________ A．Chinese smokers litter up to 4. 5 trillion butts every year B．people in the world use 2 billion plastic bags in a single day C．plastic bags cause 1 million deaths of seabirds each year worldwide D．the butts can last 20 to 1,000 years in the environment of China 小题4: What's probably the best title of the passage?. Clean Up Your A．Say Goodbye to Smokin B．Protect the Endangered Sea Animals . C．Use Paper Bags Now D．Clean Up Your Butts and Bags