When you say 28-character works, you generally mean seven-character quatrains, that is, one sentence in seven words and four sentences in the whole poem. For example, in Wang Changling's "Out of the Great Wall", the bright moon was in the sky in the Qin Dynasty, and it was closed in the Han Dynasty, but the Great Wall people in Wan Li did not return it. If Wei Qing, who attacked Longcheng, and Li Guang, the flying general, were alive today, the Huns would not be allowed to go south to spend their horses in Yinshan.
If you mean the 28 squares of your work, then you should leave some extra squares for inscription. At this time, you can write five-character quatrains. such as
Jiang Xue described by Liu Zongyuan has no birds in hundreds of mountains and no footprints in thousands of roads. A boat on the river, a fisherman wearing his webworm moth; Fishing alone is not afraid of snow and ice.
I hope I can help you.