题目

Which of the following we can’t use when we make a telephone call? A. Who’s that?       B. Who’s calling?  C. Who’s speaking?  D. Who are you? 答案：D二次函数y=2（x-1）2+3的图象的顶点坐标是（ ）A．（1，3）B．（-1，3）C．（1，-3）D．（-1，-3）