Broadly speaking, "expression skills" can include the following contents:
1. Rhetorical devices: metaphor, personification, contrast, duality, metonymy, exaggeration, pun, rhetorical question, repetition, irony, quotation, etc.
2. Allusions:
Allusions refer to the references to historical stories, myths and legends, and predecessors' quips in poetry. The former is called "allusions" and the latter is called "allusions". In fact, the function of allusions is similar to metaphor. Metaphor is to use immediate things as metaphors to express characteristics, while allusion is to use ancient things as metaphors to express meaning, and to express the present through ancient things. We need to find out what the poet wants to express first, and then find out what the allusions are, so that it is easier to see what the poet means.