Brief analysis: in the sentence "I cherish my hometown chrysanthemum far away", the word "far away" at the beginning exaggerates my distance from my hometown Chang 'an, and sets off the poet's deep homesickness. Then the poet concentrated his feelings of missing relatives and friends on Chrysanthemum in my hometown. The word "pity" not only describes the poet's attachment to his hometown chrysanthemum, but also describes the poet's long sigh and pity for his hometown chrysanthemum on the battlefield. In general, the author does not write about homesickness, but especially emphasizes the yearning and pity for the chrysanthemum in Chang 'an's hometown, and uses "hometown chrysanthemum" to represent the whole hometown of Chang 'an, which is vivid and tangible.
In the sentence "It should be opened on the battlefield", the poet just imagined that the chrysanthemums in his hometown should be opened on the battlefield, which made readers seem to see a vivid picture of war: in Chang 'an City, the streets are bloody, and in broken walls, chrysanthemums are still blooming alone. Ruins, blood everywhere, the imperial capital Chang 'an Huanghua, was ruined by the disorderly army. The imaginary words here have broken through the simple feeling of cherishing flowers and homesickness, and pinned the poet's sympathy for millions of people suffering from war, anxiety about state affairs, and desire to pacify the Anshi rebellion and realize peace at an early date.