A:都江堰
B:灵渠
C:白渠
D:大运河
已知曲线C:y=1xx>0及两点A1(x1,0)和A2(x2,0),其中x2>x1>0.过A1,A2分别作x轴的垂线,交曲线C于B1,B2两点,直线B1B2与x轴交于点A3(x3,0),那么( )
I enjoyed myself during the summer holidays.
《刷子李》这篇课文选自冯冀才的( )