Определить в предложениях сложное подлежащее: 1. This phenomenon has been found to have a wide occurrence. 2. This group of patients appears to represent a unique subgroup with anticardiolipin syndrome. 3. These factors are known to be associated with an increased risk of atherosclerosis. 4. Human milk is less likely to lead to allergic problems than other foods. 5. Thenumber of drags are known to have been available for the treatment of cardiac failures. 6. Vitamin D is known to be the antirachitic substance.