问题 选择题

将一条抛物线向左平移2个单位后得到了y=2x2的函数图象,则这条抛物线是(   )  

A.y=2x2+2

B.y=2x2-2

C.y=2(x-2)2

D.y=2(x+2)2

答案

C.

题目分析:∵y=2x2的顶点坐标为(0,0),

∴平移前的抛物线的顶点坐标为(2,0),

∴原抛物线解析式为y=2(x-2)2

故选C.

材料题

阅读材料:

       “自永乐三年奉使西洋,迄今七年,所历……三十余国,涉沧溟十万余里。观夫海洋。洪涛接天。巨浪如山。……而我之云帆高涨,昼夜星驰,涉彼狂澜。……”

请回答:

(1)该材料反映的是哪一个历史事件?说明其起止时间。

                                                                                                                                                             

(2)材料本身反映出一种什么精神?

                                                                                                                                                              

(3)这一事件的历史意义是什么?

                                                                                                                                                              

                                                                                                                                                              

单项选择题