题目

—Linda looks worried.—Yes, she didn’t know French, but she was made ______ to sing a French song in two days.A. mention                                   B. learn     C. to mention                               D. to learn 答案：D9．在直角坐标系xOy中，函数y=f（x）的图象记为I′，若在I′上任取一点M，都能在I′上找到一点N，使得$\overrightarrow{OM}$•$\overrightarrow{ON}$=0，则称图象I′为“优美图象”．下列函数的图象为“优美图象”的是（　　）A．y=2x+1B．y=log3（x-2）C．y=$\frac{2}{x}$D．y=cosx