完成课本案例7的程序的编写，并将代码及结果上传。希望同学们能够通过此案例掌握自增与自减的用法与含义。

A. is made of islands on the water
B. has many older residents
C. is expensive for people to live in
D. has millions of tourists

A. it has many problems
B. everything comes to the city by boat
C. it has so many tourists
D. everything is too expensive

A. too many old residents and too many rich people
B. too many bridges and too much water from high tides
C. high water and too many tourists
D. expensive souvenirs and too many tourists

A. there is too much water
B. the houses are few and expensive
C. there are too many residents
D. the city is too crowded