Solutions; (1) Darwin believed that in struggle for existence, individuals with favorable variation were easy to win and survive in struggle for existence. On the contrary, individuals with unfavorable mutation are prone to failure and death in struggle for existence. In other words, all living things are adaptable to the environment, which is the result of long-term natural selection;

(2) "Hearing firecrackers covering your ears" is a regular response to stimuli through the nervous system, which is called reflection. Its formation process is: firecrackers wave? 4 tympanic membrane? Six ossicles? ⑤ Cochlea? ① auditory nerve? (2) Auditory pathways in the brain? 8 body movement center? ③ Spinal cord? ⑦ Nerves innervating muscles

The muscles related to covering ears alternately contract and relax;

(3) The structure of the ear includes external ear (auricle, external auditory canal), middle ear (tympanic membrane, tympanum, ossicles) and internal ear (semicircular canal, vestibule, cochlea). The tympanic membrane and cochlea are located as follows: