Great changes have taken place in that factory. It is no longer _________ it was 20 years ago,_____

题干

Great changes have taken place in that factory. It is no longer ____

_____
it was 20 years ago,_____ it was so poorly equipped.

A：what ,whe

B：that ,which

C：what ,which

D：which ,that

上一题下一题 0.0难度选择题更新时间:2018-06-20 05:14:44

A

抛物线y=ax²+bx+c上部分点的横坐标x，纵坐标y的对应值如下表：

x	…	﹣2	﹣1	0	1	2	…
y	…	0	4	6	6	4	…

小聪观察上表，得出下面结论：①抛物线与x轴的一个交点为（3，0）； ②函数y=ax²+bx+C的最大值为6；③抛物线的对称轴是 $x = \frac{1}{2}$ ；④在对称轴左侧，y随x增大而增大．其中正确有（　　）