题目

如图，已知抛物线L1：y=x2－x－，L1交x轴于A，B（点A在点B左边），交y轴于C，其顶点为D，P是L1上一个动点，过P沿y轴正方向作线段PQ∥y轴，使PQ=t，当P点在L1上运动时，Q随之运动形成的图形记为L2．（1）若t=3，求图形L2的函数解析式；（2）过B作直线l∥y轴，若直线l和y轴及L1，L2所围成的图形面积为12，求t的值． 根据问句，选择恰当的答句。 (     ) 1. What is it?(     ) 2. Do you like this toothbrush?(     ) 3. How much is the brush?(     ) 4. Is it her comb?(     ) 5. May I borrow your soap, please?(     ) 6. What day is it? A. Sure!B. Fifteen yuan.C. Yes, it is.D. No, I don't.E. It's a comb.F. It's Thursday.