下列说法：

①将一组数据中的每个数据都加上或减去同一个常数后，均值与方差都不变；

②设有一个回归方程 $\widehat{y}=5-3x$ ，变量x增加一个单位时，y平均增加3个单位；

③线性回归方程 $\widehat{y}=bx+a$ 必经过点 $\left(\overline{x}，\overline{y}\right)$ ；

④在吸烟与患肺病这两个分类变量的计算中，从独立性检验知，有99%的把握认为吸烟与患肺病有关系时，我们说现有100人吸烟，那么其中有99人患肺病．其中错误的个数是（   ）

    The Roses（罗斯一家）like having picnics on Sundays. This Sunday they want to go to the Red Park. Jack and Mike, their sons, get up early in the morning. Jack puts on a shirt and jeans, and Mike puts on a T-shirt and jeans. They also put on their running shoes. After that they help their mother put bread, milk, eggs and some fruit in a basket and carry it to the car. Mrs. Rose also takes four glasses of juice with her. The little dog Jerry is running after her. It wants to go with them, too. They are all very happy.

下列说法中，运动状态没有发生改变的是（　　）