Were you the first or the last child in your family? Or were you a middle or an only child? Some people think it matters where you were born in your family. But there ____(be)different ideas about____birth order means. Some people say that the oldest children,____are smart and strong-willed, are very likely to succeed. The reason for this is simple. Parents have a lot of time for their first child and give him or her a lot of attention. An only child will succeed for____same reason.

    What happens to the other children in the family? Middle children don't get so much attention, so they don't feel that important. If a family has many children, the middle one sometimes gets____(lose)in the crowd. The youngest child,____ often gets special treatment. Often this child grows up to be funny. But a recent study saw things quite  ____(different). The study ____(find) that first children believed in family rules. They didn't take many chances in ____(they)lives. They usually followed orders. Rules didn't mean as much to later children in the family. They took chances and they often ____(do) better in life.

① 设计甲实验的目的是研究钢球动能的大小与____的关系；设计乙实验的目的是研究小车的运动与所受____的关系．

② 甲实验是通过观察____，从而间接判断钢球动能的大小；乙实验是通过观察小车在粗糙程度不同的水平面上运动的远近，推理得出：____。