【简答题】Have you ever rubbed your hands together when they get cold? Why do we do that? We do that for friction . Friction happens when two things that aren’t very smooth (光滑的) rub together to make heat energ...
【简答题】Have you ever rubbed your hands together when they get cold? Why do we do that? We do that for friction . Friction happens when two things that aren’t very smooth rub together to make heat energy. The...