The Lantern Festival is an important traditional festival in my country. "The star falls after the Han Dynasty, and the moon hangs from the building." is a portrayal of its grand occasion by Lu Zhaoli

The Lantern Festival is an important traditional festival in my country. "The star falls after the Han Dynasty, and the moon hangs from the building." is a portrayal of its grand occasion by Lu Zhaolin, a famous poet in the Tang Dynasty.

(1)①Because in a compound, the algebraic sum of positive and negative valences is 0, so the total number of positive valences and the total number of negative valences of elements in the compound are equal. The valence of NO3 is -1, so the valence of Sr is +2;

②Sulfur burns in oxygen to form sulfur dioxide. The chemical reaction formula is: S+O2? Ignite?.?SO2;

③The generated sulfur dioxide dissolves in water and can form acid rain. The pollution caused by setting off fireworks to the environment is the formation of acid rain;

(2) It is necessary to make the Kongming Lanterns fly higher, farther and safer , the material of the lampshade is light and not easy to burn; the fuel has a large burning calorific value and takes a long time. Therefore, the answer is: not easy to burn and takes a long time to burn;

(3) The materials in gas stations, liquefied gas stations, oil depots and other places are flammable and have sufficient oxygen. It is usually very safe because the ignition point of the material has not been reached. Once a sky lantern with an outer flame temperature of more than 300 degrees falls to these places and reaches the ignition point, it will cause a fire.

So the answer is: (1) ①+2 valence; ②S+O2?ignite?.?SO2; ③form acid rain;

(2) not easy to burn; long burning time;

(3)C.