完形填空
For a century and a half the piano has been one of the most popular solo instruments for Western music. Unlike string and wind instruments, the piano is completely【C1】______, as it is able to play both the melody and its accompanying harmony at the same time. For this reason, it became the favorite household 【C2】______of the nineteenth century. The【C3】______of the piano can be traced to the early keyboard instruments of the fifteenth and sixteenth centuries — the spinet, the dulcimer, and the virginal. In the seventeenth century the organ, the clavichord (古钢琴) , and the harpsichord (拨弦键琴 ) became the 【C4】______ instruments of the keyboard group, a domination they maintained until the piano replaced them at the end of the eighteenth century. The clavichord's tone was metallic and never powerful;【C5】______, because of the variety of tone possible to it, many composers found the clavichord a sympathetic instrument for concert use, but the character of the tone could not be【C6】______save by mechanical or structural devices. The piano was【C7】______ in the early eighteenth century by a harpsichord maker in Italy (though musicologists point out several previous instances of the instrument). This instrument was called a piano e forte (soft and loud), to indicate its dynamic flexibility; its strings were【C8】______by a recoiling hammer with a felt-padded head. The wires were much heavier in the earlier instruments. A【C9】______of mechanical improvements continuing well into the nineteenth century, including the introduction of pedals to sustain tone or to soften it, the perfection of a metal frame and steel wire of the finest quality, finally produced an instrument【C10】______of many tonal effects from the most delicate harmonies to an almost orchestral fullness of sound, from a liquid, singing tone to a sharp, percussive (打击乐器的) brilliance. A. autobiography B. struck C. perfected D. abandoned E. ancestry F. reliable G. self-sufficient H. nevertheless I. therefore J. instrument K. varied L. series M. capable N. piece O. chief