Read through the following arguments and identify the author’s position. Fill in the blanks with the number of the sentence you choose. 直接填数字,不加任何标点符号! Argument 1: 1. The nature and origin of disease was unclear until relatively recently. 2. At the end of the nineteenth century, Koch, a Prussian scientist, introduced a set of procedures( 程序 ) now known as Koch’s postulates( 假定 ) . 3. He experimented with bacterial colonies( 细菌群落 ) cultivated in the laboratory, made from the blood of dying cattle. 4. When these cultures were injected into healthy live cattle, these also caught the same disease. 5. At the time, these findings were astonishing. 6. Koch had been able to provide proof to support the theory that disease was spread by germs. 7. He contributed one of the most important methodological advances in the history of medicine. The position : ___________