选文第⑤段中划线的“这些做法”具体指代的内容有哪些？
①小书包公益活动；②建立小小图书馆；③儿童文学作家推广阅读；④老师外出学习如何开展少儿阅读推广活动。
从所给出的单词中选出合适的完成对话。
swim ride cousin What is
Tom: Hello, Peter. Who is that boy?
Peter: He is my____. He is my uncle's son.
Tom: What____ his name?
Peter: His name is Jim.
Tom: Can he____?
Peter: Yes, he can. He likes swimming.
Tom: Good! I like it, too.____about you?
Peter: No, I can't swim. But I can ____a bike.
读中国地图，回答下列问题。
如图所示，甲、乙、丙三个光滑斜面，它们的高度相同、倾角不同，θ1＜θ2＜θ3．现让完全相同的物块沿斜面由静止从顶端运动到底端．关于物块沿不同斜面运动时重力做功W和重力做功的平均功率P，下列说法正确的是（ ）
