命题“$\forall x\in R,x^2-3x+2\ge 0$”的否定是（  ）

C

    The government in China plans to end its one-child policy (政策) and let families have two children instead. The plan was meant to balance (平衡) population development and stop a falling birth rate (出生率).

    China started the one-child policy in the 1980s. But the government allowed only a small number of couples to have two children. For example, some families in the countryside could have two children, if the first-born child is a girl. In 2013, the Chinese government gave other couples a chance to have two children if one of them was an only child.

    Jiang Quanbao, a population expert, explained how Chinese families react to the newest policy. "Lots of young people in the cities are no longer interested in having a second child," he said.

    At the end of 2014, China had a population of 1.37 billion people. But the labor market population will drop in 35 years. That is to say, the country will be in great need of labor by the year 2050. With the "two children" policy, an increase in births can solve this problem.

INPUT　“x=”；x

IF　x>=4　THEN

　y=x-3

ELSE

　①

END IF

PRINT　y

END

将一组数据中的每一个数减去40后，所得新的一组数据的平均数是2，则原来那组数据的平均数是（　　）

在倾角为θ的光滑斜面上有两个用轻弹簧相连接的物块A、B，它们的质量均为m，弹簧劲度系数为k，C为一固定挡板，系统处于静止状态．现用一恒力F沿斜面方向拉物块A使之向上运动，当物块B刚要离开C时，A的速度为v，则此过程（弹簧的弹性势能与弹簧的伸长量或压缩量的平方成正比，重力加速度为g）（   ）