1._______ at all is worth doing well.
A. Whatever is worth doing B. That is worth doing
C. What is worth doing it D. Whatever is worth doing it
2.He bought a house for his children ________.
A. lived in B. to live in C. Lived D. to live
3.By the middle of the 21st century，the vast majority of the world‘s population will be living in cities _______ in the country.