Release the comparison of wings: wings are next to wings. Double flight: fly in pairs. Metaphor conjugal love, companionship, or congeniality between men and women.
In Er Ya Shi Di: "There are some flying birds in the south, so it's better than not flying, so it's called walking.
the method is linked; As predicate, object and complement; Metaphor husband and wife congenial, move forward side by side.