(Left) There are many famous tourist attractions in Koukouzhou area of the Yangtze River, including Suzhou Gardens in Jiangsu Province and Hangzhou West Lake in Zhejiang Province.

(Why) Zhouzhou area of the Yangtze River estuary has formed the largest urban agglomeration in China. The core city of the Yangtze River Estuary Zhou Urban Agglomeration is Shanghai, which is the largest city in China and the most important comprehensive industrial city in China. There are more mineral resources in this area than hers. Iron ore imported from Australia formed the steel industry. The reason is that Shanghai has convenient transportation and a vast consumer market.

So the answer is:

(3) Hangzhou; Nanjing;

(left) Suzhou gardens; Hangzhou West Lake;

(he) Shanghai; Comprehensive; Shanghai has convenient transportation and a broad consumer market.