A: The article first talks about the classification of swallows, then selects various representative swallows to explain, and finally talks about the functions of swallows.

The article quotes many poems, please choose one of them to enjoy.

A: The article quotes "Try to live in the nest" to illustrate the phenomenon that some swallows will return to the nest next year, which also makes the article more vivid.

Please appreciate the underlined sentences in the fourth paragraph from the perspective of applying interpretation methods.

A: The method of comparison is adopted. Through comparison, the characteristics of golden waist are highlighted.

4. Grasping the typical characteristics of things and introducing things is a major feature of expository writing. Please choose an example from the text to illustrate.

A: In order to introduce Jin Siyan, the author highlighted the nesting characteristics of Jin Siyan with the help of people's general understanding of bird's nests.

Extended data

Morphological functions of swallows:

1. Swallows' slender bodies can reduce flight resistance. Swallow's wing shape has a high aspect ratio, which means that it can produce great lift and little resistance. But this aerodynamic efficiency is at the expense of reducing maneuverability.

2. The tail feathers of some species are very long, which can increase the lift. It acts like the flap of an airplane, ensuring the airflow to pass through the wings smoothly, and can delay the airflow when the swallow is ready to land, so that the swallow can fly and stop without increasing the resistance.