短語詞組短語principal l focus 主焦點(diǎn)the principal focus system 主聚焦系統(tǒng)secondary principal focus 後焦點(diǎn)principal focus system 主聚焦系統(tǒng)anterior principal focus 前主焦點(diǎn)the principal focus 主焦點(diǎn)principal focus distance 主距 返回 principal focus