The round pen is a "missing mark"; Fang Bi is a "sand with a cone in the painting". Internal struggle is a book of strength, while external expansion is a book of strength. The king fights among himself, and Xiao Wang expands outside; Liu Ou's internal struggle, Zhao Yan's external expansion, heather and Sui Liangren are in between. But this is only a relative statement, and the mechanical division is not clear about them. In most cases, it is used by Fiona Fang.
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