(1) Bryophytes live in a humid environment. They have no real roots, only false roots, which can't support the aboveground parts, but they only have stems and leaves, but there is no conducting tissue in the stems and leaves, so they can't transport a lot of nutrients for the plants, so the plants are relatively short.

(2) The leaves of bryophytes have only one layer of cells, and toxic gases such as sulfur dioxide can easily invade the leaf cells from the back and abdomen, threatening the survival of bryophytes. Therefore, people usually use them as indicator plants to monitor the degree of air pollution.

(3) As can be seen from the data in the table, the closer to the pollution source, the longer the pollution time and the more bryophytes die. It shows that the harm degree of bryophytes is related to the distance from the pollution source and the pollution time. The closer to the pollution source, the longer the pollution time and the greater the harm.

(4) In order to reduce the environmental pollution caused by coal-fired power generation, attention should be paid to treating the discharged waste gas, planting more plants that can absorb sulfur dioxide around the factory, and using coal with less sulfur content as fuel.

So the answer is: (1) wet; Stem; Leaves; Root; Stem; Leaves;

(2) 1; Monitoring;

(3) distance; Time; Pollution time;

(4) (1) Use low-sulfur coal as fuel; (2) Harmless treatment of the discharged waste gas; There are many kinds of plants around the factory that can absorb toxic gases such as sulfur dioxide.