阅读理解。 Parts of Africa are covered by a dark cloud. But this is no rain cloud. It is a living cloud made of billions of locusts (蝗虫) that are traveling across the continent eating everything in their path. And now in the battle to stop this disaster, a radio station in Senegal, West Africa, is offering listeners 50 kilograms of rice if they can catch and kill 50 kilograms of locusts. 'We think this idea will get more people to take part in the war on the locusts,' said Abdoulaye Ba, from Sud-Fm, a radio station in one of Senegal's worst affected area . This is West Africa's biggest locust disaster in 15 years, and it is moving east, causing huge damage to crops. As they move they produce young and increase their number and will soon threaten (威胁) Sudan in the northeast of Africa. Some say it could reach Asia. Experts say the harmful effect on crops in areas already suf-fering from food shortage and war could cause many people to go hungry. Governments in the areas are not well equipped to fight the pest. Although leaders of 12 countries have agreed on a plan, it is not expected to be enough. 'We are now treating 6,000 hectares (公顷) per day with pesticide (杀虫剂 ), but we need to treat 20,000 hectares per day in order to have any hope of controlling this disaster,' said Mohamed Abdallahi Ould Babah, director of locust control in Mauritania. Requests are being made for international aid, which is the only way to limit the disaster, the UN's Food and Agricul-ture Organization warned. 1. By using ' dark cloud' to describe locusts in the first para-graph, the author of the article ________. A. showed the size and speed of the mass of locusts B. suggested the great damage that locusts can cause C. warned that locusts would sweep the continent like rain clouds D. both A and B 2. The story is mainly about ______. A. West Africa's united effort in fighting a disaster B. the difficulty in controlling locusts C. how locusts caused great damage to West Africa D. a struggle to fight against a disaster brought by locusts in West Africa 3. The locust disaster ______. A. would be even more serious in Asia B. is (was)out of control C. affected only the warning areas D. can not be stopped unless twice as much pesticide is provided for the affected areas 4. Which of the following is WRONG ? A. Sud-Fm offered a reward for fighting locusts so that more people would join in the effort. B. Senegal is to the southwest of Sudan. C. The locusts can cause such damage mainly because it has no natural enemy in West Africa. D. 12 countries affected by locusts have united but still lack pesticide.