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  3. The human ear contains the organ for hearing and the organ for balance. Both organs involve fluid-filled channels containing hai

The human ear contains the organ for hearing and the organ for balance. Both organs involve fluid-filled channels containing hai

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问题     The human ear contains the organ for hearing and the organ for balance. Both organs involve fluid-filled channels containing hair cells that produce electrochemical impulses when the hairs are stimulated by moving fluid. The ear can be divided into three regions: outer, middle, and inner. The outer ear collects sound waves and directs them to the eardrum separating the outer ear from the middle ear. The middle ear conducts sound vibrations through three small bones to the inner ear. The inner ear is a network of channels containing fluid that moves in response to sound or movement. To perform the function of hearing, the ear converts the energy of pressure waves moving through the air into nerve impulses that the brain perceives as sound. Vibrating objects, such as the vocal cords of a speaking person, create waves in the surrounding air. These waves cause the eardrum to vibrate with the same frequency. The three bones of the middle ear amplify and transmit the vibrations to the oval window, a membrane on the surface of the cochlea, the organ of hearing. Vibrations of the oval window produce pressure waves in the fluid inside the cochlea. Hair cells in the cochlea convert the energy of the vibrating fluid into impulses that travel along the auditory nerve to the brain.
    The organ for balance is also located in the inner ear. Sensations related to body position are generated much like sensations of sound. Hair cells in the inner ear respond to changes in head position with respect to gravity and movement. Gravity is always pulling down on the hairs, sending a constant series of impulses to the brain.
    When the position of the head changes — as when the head bends forward — the force on the hair cells changes its output of nerve impulses. The brain then interprets these changes to determine the head’s new position.
It can be inferred from paragraphs 2 and 3 that the cochlea is a part of______.
选项 A、the outer ear
B、the eardrum
C、the middle ear
D、the inner ear
答案D
解析 第二段最后一句“The inner ear is a network of channels containing fluid…”，第三段中“…the cochlea，the organ of hearing”和“…the fluid inside the cochlea．Haircells in the cochlea convert the energy of the vibrating fluid…”可得知，内耳是包含液体的渠道网络，而该液体位于耳蜗中，因此，耳蜗是内耳的一部分。故答案为D。
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