题目

Doris Lessing was born in 1919 in Persia, moving as a child with her family to southern Rhodesia, now Zimbabwe, where she stayed in school only to the age of 14. A year after moving to London, she published her first novel in 1950. The Grass is Singing examines unbridgeable racial conflict in colonial Africa through the eyes of a white farmer's wife and her black servant. Her literary breakthrough came in 1962 with publication of The Golden Notebook, seen by many, though not necessarily Lessing, as a pioneering work of modern feminism（女权运动）. A disjointed study of the mind of the ma在一个周长40cm的正方形内画一个最大的圆，这个圆的周长是多少？