The main contents of air quality forecast include: primary pollutants, air pollution index and air quality grade, and the corresponding relationship between air pollution and air quality grade.

(1) According to the table data, it can be seen that the city prone to acid rain in the above cities is Kunming.

(2) The air pollution index of Tianjin is 82, and the comparison table is 1. It can be seen that 82 is between 50- 100, and the quality is good within this range, and the level is II.

(3) As can be seen from Table 2, the primary pollutant in Tianjin is inhalable particulate matter, which may be due to the urban reconstruction, which protects the air by sprinkling water on the construction site and reduces all kinds of dust in the construction industry.

So the answer is: (1) Kunming;

(2)Ⅱ;

(3) The construction site is often watered to protect the air and reduce all kinds of dust in the construction industry.