определите тип инфинитивного оборота (сложное подлежащее, сложное дополнение или оборот с предлогом for): 1. About 50 per cent of Lake Baikal water proved to have been polluted since the Baikal plant has begun its work. 2. We know many cities throughout the world to suffer from air pollution. 3. It is for you to decide which of two methods to use.