Переделайте предложения из действительного залога в страдательный. 1. He is writing a letter at the moment. 2. John was preparing report all day yesterday. 3.We are learning grammar now. 4. At present mankind is making considerable investments to eliminate air pollution. 5. Today the changes in the global climate and water balance are bringing about serious changes in the environment. 6. Many scientists are constantly carrying out experimental work to solve the problem of environment protection. 7. The company is making plans for the future.