Hello! I'm Wang Lin. I like sports very much. Basketball is 1 favourite sport. Tom is my friend. He is an 2  boy. He is from America. He is 12 3  old. He likes sports, too. He has（有）a big ball collection（收藏物） 4  his room. There are 5  balls in the room. Tom's  6  aren't at home.  7  his sister Dee is at home. She is in the room now. Her favourite 8  is football. I don't like  9  because（因为）she isn't nice to me. I want（想要）to have a 10 collection too. Then I can have many balls. Do you want to have one?

在探究影响酶活性的条件的实验中，不属于影响过氧化氢酶活性的因素是

两分子间的斥力和引力的合力F与分子间距离r的关系如图中曲线所示，曲线与r轴交点的横坐标为r₀，相距很远的两分子在分子力作用下，由静止开始相互接近．若两分子相距无穷远时分子势能为零，下列说法正确的是（  ）

某同学为了体验伽利略对自由落体运动的研究过程，将一重为10N的铅球从教学楼上自由释放，1s末速度大小为10m/s，则此时重力的功率为（   ）