题目

—Why did you plant so many trees? — ______ the environment. A. Improve    B. To Improve    C. Improved     D. Improving 答案：B（2008•常德）把抛物线y=x2向右平移2个单位，再向上平移1个单位，所得的抛物线的解析式为（ ）A．y=（x-2）2+1B．y=（x-2）2-1C．y=（x+2）2+1D．y=（x+1）2-2