Translate the words given in brackets into English and then translate the sentences:
1. To fight against any infectious disease successfully a doctor (должен) know its origin. 2. The redness on the lateral surface of the arm (может) disappear after the treatment. 3. To determine the origin of the tobacco mosaic disease Ivanovsky (должен был) carry out many experiments on the plants. 4. The doctor (следует) know all the properties of a drug before he gives it to the patient. 5. At the next conference one of the researchers of this laboratory (нужно будет) report on his discovery in detail. 6. The medical students (будет разрешено) operate on the patients only in the fifth year. 7. It is only in the presence of oxygen that aerobic microorganisms (могут) multiply rapidly