Rhode Island was the【C1】______ of American tennis: when the United States National Championships (now the United States Open) were inaugurated in 1881, they were played on the【C2】______ of the Newport Casino. Like Wimbledon, the 【C3】______ became known by its【C4】______ after it was moved to Forest Hills, N.Y., in 1915. That tournament was played on grass until 1975,【C5】______ clay courts were installed to equalize Grand Slam competition.
【C6】______ lawn tennis was devised as a more accessible【C7】______ of the old court game played in French chateaus, the manicured grass courts it【C8】______ were the playgrounds of the elite. Dirt courts brought another【C9】______ of tennis players into competition.
The【C10】______ of cement courts in the【C11】______ parks of southern California finally dispelled the sport's country-club image.【C12】______ , by the 1980s the word lawn had been【C13】______ from the names of all the associations that governed the game.
Tennis can be played by two persons in【C14】______ or by four in doubles. The【C15】______ of the game is to hit the ball【C16】______ a net and keep it in play【C17】______ the opponent loses the point by【C18】______ a good return. The playing area is【C19】______ into two service courts and a backcourt on each side of the【C20】______ . The service area on the player's right is called the deuce court; the one on the left, the ad court.
【C1】

A. cradle
B. basis
C. foundation
D. source