2. They are all seven-tone ancient poems.
3. All of them were written in the calendar year.
4. They are all lyrical by borrowing scenery.
5. The main tone is sad.
6. Poetry embodies the characteristics of Du Fu's poetry: depression and frustration.
7. Both vividly express the poet and the turmoil of the current situation, as well as the author's ups and downs of anxiety and the injustice of the aftermath.