下图反映了某时期我国公有经济和私有经济成分的比例情况,这种情况最早应出现于( )
A:新中国成立后
B:三大改造完成后
C:“大跃进”运动时期
D:人民公社化运动时期
This is a photo of my family . I'm John . I'm ten . My sister is seven . We are in the same school .My grandparents are Americans . My father is 42 .He is a driver . My mother is 40 . She is a teacher . We are very happy .
下列一元二次方程中,有两个不相等实数根的方程是( )