Переведите предложения, содержащие субъектный и объектный инфинитивные обороты, инфинитив в функции определения.
1. The coke must be strong enough to resist the weight of overburden in the blast furnace.
2. Coal is one of the first minerals to have been found by man in nature.
3. Scientists affirm coal to have been used by the Chinese long before it was used in Europe.