[单项选择]Resistance to Malaria 1. "Our job", said the health officer, "is to spray the walls of every house in every town and village in the malaria parts of Mexico". You may be surprised to learn that there are about ninety-nine thousand separate villages and towns. Some are big places like Mexico City, some are single houses deep in the jungles or upon the mountain-tops. The men working with our programme say that most of these localities lie within districts warm enough for the malaria-carrying mosquitoes to live in and spread the disease. That means that we must plan to spray the walls of nearly three million house once or twice a year for five years." 2. "We have studied everything very carefully" , the officer continued. "Our advance guards have drawn maps of some forty thousand parts of the country for use by the spray teams. Each house in the malaria districts has been given a special number. The United Nations has given us cars and trucks to carry the spray teams and their tools,