【单选题】

New York, London, Paris and other big cities are exciting places to live in. There are (41) interesting things to see and to do. You can go to (42) kinds of museums, plays and films. You can also (43) things from all over the worlD、

But there are serious problems in big cities, (44) . It’s (45) to live there, and there are too many people in some places of big cities.Every year many people move to the cities, because they can (46) find jobs, to study at good schools and to receive good medical care there.But (47) these people cannot find work or a good place to live in.Also too many people in a small (48) makes it hard to keep cities (49) and clean.
Some people enjoy living in big cities, others do not. (50) people move to a big city, they should think about the problems of living there.
A．sell
B．buy
C．borrow