-a2-11-a=-(a+1)(a-1)1-a=(a+1)(a-1)a-1=a+1，
故选A．
下列各句中，加点成语使用恰当的一项是（）。
A.莫斯科时间2月7日20点14分，第22界冬季奥林匹克运动会开幕式在俄罗斯度假胜地索契市举行，金碧辉煌的开幕式演出吸引了全球约30亿的电视观众
B.联合国特别协调员卡洛，兴致勃勃地参观正在塞浦路斯利马索尔港补给的中国海军盐城舰，高度赞扬中国政府为政治解决叙利亚化学武器问题所做的努力。
C.3月21日，“雪龙”号上的中国第30次南极科学考察队在澳大利亚人员配合下，倾巢出动，火速前往搜寻马航MH370失联客机
D.《警察日记》和《白日焰火》作为国际电影节获奖影片，对表达中国文化自信力方面的贡献，可谓两全其美
Americans use more water than any other people in the world. If we continue to use water at the rate we do now, we will soon not have enough to meet our needs. In 1980, 40 billion gallons were used each day in the United States. In 1990, 700 billion gallons were used. The average Americans uses almost 90 gallons of water a day for personal use. And much move water is needed to make the things American people like to have. For example, it takes thousands of gallons of water to make one pound of beef for the dinner table. It takes more than 100,000 gallons of water to make a car. If we include these uses of water, the average American uses about 2000 gallons of water a day.
The best title for the passage is ______.
A．Water Use in the United States
B．The Problem of Water Use
C．Water Use in the World
D．Water Use in the Twentieth Century
